diff --git a/README.md b/README.md
index 3aa5149..c27ab2e 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,10 @@
 * These files are part of my Udemy course about Terraform
 * Course URL: https://www.udemy.com/learn-devops-infrastructure-automation-with-terraform/?couponCode=TERRAFORM_GIT
 
+# Compatibility
+
+* This is the >=terraform-0.12 branch. For compatibility with older versions, use the terraform-0.11 branch.
+
 # Demo overview
 Demo Directory | Description
 ------------ | -------------
diff --git a/demo-1/instance.tf b/demo-1/instance.tf
index d2a78b5..4de24ff 100644
--- a/demo-1/instance.tf
+++ b/demo-1/instance.tf
@@ -1,4 +1,5 @@
 resource "aws_instance" "example" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
 }
+
diff --git a/demo-1/provider.tf b/demo-1/provider.tf
index 9f26b63..696b517 100644
--- a/demo-1/provider.tf
+++ b/demo-1/provider.tf
@@ -1,6 +1,6 @@
 provider "aws" {
-    access_key = "${var.AWS_ACCESS_KEY}"
-    secret_key = "${var.AWS_SECRET_KEY}"
-    region = "${var.AWS_REGION}"
+  access_key = var.AWS_ACCESS_KEY
+  secret_key = var.AWS_SECRET_KEY
+  region     = var.AWS_REGION
 }
 
diff --git a/demo-1/vars.tf b/demo-1/vars.tf
index 1a0b3dc..5dc7c2d 100644
--- a/demo-1/vars.tf
+++ b/demo-1/vars.tf
@@ -1,13 +1,19 @@
-variable "AWS_ACCESS_KEY" {}
-variable "AWS_SECRET_KEY" {}
+variable "AWS_ACCESS_KEY" {
+}
+
+variable "AWS_SECRET_KEY" {
+}
+
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-0d729a60"
   }
 }
+
diff --git a/demo-1/versions.tf b/demo-1/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-1/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-10/cloudinit.tf b/demo-10/cloudinit.tf
index 5e04888..4c0b056 100644
--- a/demo-10/cloudinit.tf
+++ b/demo-10/cloudinit.tf
@@ -1,29 +1,30 @@
 data "template_file" "init-script" {
-  template = "${file("scripts/init.cfg")}"
-  vars {
-    REGION = "${var.AWS_REGION}"
+  template = file("scripts/init.cfg")
+  vars = {
+    REGION = var.AWS_REGION
   }
 }
-data "template_file" "shell-script" {
-  template = "${file("scripts/volumes.sh")}"
-  vars {
-    DEVICE = "${var.INSTANCE_DEVICE_NAME}"
-  }
-}
-data "template_cloudinit_config" "cloudinit-example" {
 
-  gzip = false
+data "template_file" "shell-script" {
+  template = file("scripts/volumes.sh")
+  vars = {
+    DEVICE = var.INSTANCE_DEVICE_NAME
+  }
+}
+
+data "template_cloudinit_config" "cloudinit-example" {
+  gzip          = false
   base64_encode = false
 
   part {
     filename     = "init.cfg"
     content_type = "text/cloud-config"
-    content      = "${data.template_file.init-script.rendered}"
+    content      = data.template_file.init-script.rendered
   }
 
   part {
     content_type = "text/x-shellscript"
-    content      = "${data.template_file.shell-script.rendered}"
+    content      = data.template_file.shell-script.rendered
   }
-
 }
+
diff --git a/demo-10/instance.tf b/demo-10/instance.tf
index ad7b32b..4a065b6 100644
--- a/demo-10/instance.tf
+++ b/demo-10/instance.tf
@@ -1,33 +1,32 @@
 resource "aws_instance" "example" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.allow-ssh.id}"]
+  vpc_security_group_ids = [aws_security_group.allow-ssh.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 
   # user data
-  user_data = "${data.template_cloudinit_config.cloudinit-example.rendered}"
-
+  user_data = data.template_cloudinit_config.cloudinit-example.rendered
 }
 
 resource "aws_ebs_volume" "ebs-volume-1" {
-    availability_zone = "eu-west-1a"
-    size = 20
-    type = "gp2" 
-    tags {
-        Name = "extra volume data"
-    }
+  availability_zone = "eu-west-1a"
+  size              = 20
+  type              = "gp2"
+  tags = {
+    Name = "extra volume data"
+  }
 }
 
 resource "aws_volume_attachment" "ebs-volume-1-attachment" {
-  device_name = "${var.INSTANCE_DEVICE_NAME}"
-  volume_id = "${aws_ebs_volume.ebs-volume-1.id}"
-  instance_id = "${aws_instance.example.id}"
+  device_name = var.INSTANCE_DEVICE_NAME
+  volume_id   = aws_ebs_volume.ebs-volume-1.id
+  instance_id = aws_instance.example.id
 }
 
diff --git a/demo-10/key.tf b/demo-10/key.tf
index 0d3c220..58b093f 100644
--- a/demo-10/key.tf
+++ b/demo-10/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/demo-10/provider.tf b/demo-10/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-10/provider.tf
+++ b/demo-10/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-10/securitygroup.tf b/demo-10/securitygroup.tf
index 05c0e12..1ec204b 100644
--- a/demo-10/securitygroup.tf
+++ b/demo-10/securitygroup.tf
@@ -1,21 +1,22 @@
 resource "aws_security_group" "allow-ssh" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-ssh"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "allow-ssh"
   }
 }
+
diff --git a/demo-10/vars.tf b/demo-10/vars.tf
index 179eca7..b9430d1 100644
--- a/demo-10/vars.tf
+++ b/demo-10/vars.tf
@@ -1,20 +1,25 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
 variable "INSTANCE_DEVICE_NAME" {
   default = "/dev/xvdh"
 }
+
diff --git a/demo-10/versions.tf b/demo-10/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-10/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-10/vpc.tf b/demo-10/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-10/vpc.tf
+++ b/demo-10/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/demo-11/provider.tf b/demo-11/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-11/provider.tf
+++ b/demo-11/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-11/route53.tf b/demo-11/route53.tf
index b4d26de..2ec049d 100644
--- a/demo-11/route53.tf
+++ b/demo-11/route53.tf
@@ -1,34 +1,38 @@
 resource "aws_route53_zone" "newtech-academy" {
-   name = "newtech.academy"
+  name = "newtech.academy"
 }
+
 resource "aws_route53_record" "server1-record" {
-   zone_id = "${aws_route53_zone.newtech-academy.zone_id}"
-   name = "server1.newtech.academy"
-   type = "A"
-   ttl = "300"
-   records = ["104.236.247.8"]
+  zone_id = aws_route53_zone.newtech-academy.zone_id
+  name    = "server1.newtech.academy"
+  type    = "A"
+  ttl     = "300"
+  records = ["104.236.247.8"]
 }
+
 resource "aws_route53_record" "www-record" {
-   zone_id = "${aws_route53_zone.newtech-academy.zone_id}"
-   name = "www.newtech.academy"
-   type = "A"
-   ttl = "300"
-   records = ["104.236.247.8"]
+  zone_id = aws_route53_zone.newtech-academy.zone_id
+  name    = "www.newtech.academy"
+  type    = "A"
+  ttl     = "300"
+  records = ["104.236.247.8"]
 }
+
 resource "aws_route53_record" "mail1-record" {
-   zone_id = "${aws_route53_zone.newtech-academy.zone_id}"
-   name = "newtech.academy"
-   type = "MX"
-   ttl = "300"
-   records = [
-     "1 aspmx.l.google.com.",
-     "5 alt1.aspmx.l.google.com.",
-     "5 alt2.aspmx.l.google.com.",
-     "10 aspmx2.googlemail.com.",
-     "10 aspmx3.googlemail.com."
-   ]
+  zone_id = aws_route53_zone.newtech-academy.zone_id
+  name    = "newtech.academy"
+  type    = "MX"
+  ttl     = "300"
+  records = [
+    "1 aspmx.l.google.com.",
+    "5 alt1.aspmx.l.google.com.",
+    "5 alt2.aspmx.l.google.com.",
+    "10 aspmx2.googlemail.com.",
+    "10 aspmx3.googlemail.com.",
+  ]
 }
 
 output "ns-servers" {
-   value = "${aws_route53_zone.newtech-academy.name_servers}"
+  value = aws_route53_zone.newtech-academy.name_servers
 }
+
diff --git a/demo-11/vars.tf b/demo-11/vars.tf
index 7c29d8c..ac7990c 100644
--- a/demo-11/vars.tf
+++ b/demo-11/vars.tf
@@ -1,3 +1,4 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
diff --git a/demo-11/versions.tf b/demo-11/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-11/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-12/instance.tf b/demo-12/instance.tf
index d3abc89..8e57338 100644
--- a/demo-12/instance.tf
+++ b/demo-12/instance.tf
@@ -1,14 +1,14 @@
 resource "aws_instance" "example" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.example-instance.id}"]
+  vpc_security_group_ids = [aws_security_group.example-instance.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
-
+  key_name = aws_key_pair.mykeypair.key_name
 }
+
diff --git a/demo-12/key.tf b/demo-12/key.tf
index 0d3c220..58b093f 100644
--- a/demo-12/key.tf
+++ b/demo-12/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/demo-12/output.tf b/demo-12/output.tf
index b698a6b..079b025 100644
--- a/demo-12/output.tf
+++ b/demo-12/output.tf
@@ -1,6 +1,8 @@
 output "instance" {
-  value = "${aws_instance.example.public_ip}"
+  value = aws_instance.example.public_ip
 }
+
 output "rds" {
-  value = "${aws_db_instance.mariadb.endpoint}"
+  value = aws_db_instance.mariadb.endpoint
 }
+
diff --git a/demo-12/provider.tf b/demo-12/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-12/provider.tf
+++ b/demo-12/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-12/rds.tf b/demo-12/rds.tf
index 21f4a73..9aee3c6 100644
--- a/demo-12/rds.tf
+++ b/demo-12/rds.tf
@@ -1,40 +1,39 @@
 resource "aws_db_subnet_group" "mariadb-subnet" {
-    name = "mariadb-subnet"
-    description = "RDS subnet group"
-    subnet_ids = ["${aws_subnet.main-private-1.id}","${aws_subnet.main-private-2.id}"]
+  name        = "mariadb-subnet"
+  description = "RDS subnet group"
+  subnet_ids  = [aws_subnet.main-private-1.id, aws_subnet.main-private-2.id]
 }
 
 resource "aws_db_parameter_group" "mariadb-parameters" {
-    name = "mariadb-parameters"
-    family = "mariadb10.1"
-    description = "MariaDB parameter group"
+  name        = "mariadb-parameters"
+  family      = "mariadb10.1"
+  description = "MariaDB parameter group"
 
-    parameter {
-      name = "max_allowed_packet"
-      value = "16777216"
-   }
-
-}
-
-
-resource "aws_db_instance" "mariadb" {
-  allocated_storage    = 100    # 100 GB of storage, gives us more IOPS than a lower number
-  engine               = "mariadb"
-  engine_version       = "10.1.14"
-  instance_class       = "db.t2.small"    # use micro if you want to use the free tier
-  identifier           = "mariadb"
-  name                 = "mariadb"
-  username             = "root"   # username
-  password             = "${var.RDS_PASSWORD}" # password
-  db_subnet_group_name = "${aws_db_subnet_group.mariadb-subnet.name}"
-  parameter_group_name = "${aws_db_parameter_group.mariadb-parameters.name}"
-  multi_az             = "false"     # set to true to have high availability: 2 instances synchronized with each other
-  vpc_security_group_ids = ["${aws_security_group.allow-mariadb.id}"]
-  storage_type         = "gp2"
-  backup_retention_period = 30    # how long you’re going to keep your backups
-  availability_zone = "${aws_subnet.main-private-1.availability_zone}"   # prefered AZ
-  skip_final_snapshot = true   # skip final snapshot when doing terraform destroy
-  tags {
-      Name = "mariadb-instance"
+  parameter {
+    name  = "max_allowed_packet"
+    value = "16777216"
   }
 }
+
+resource "aws_db_instance" "mariadb" {
+  allocated_storage       = 100 # 100 GB of storage, gives us more IOPS than a lower number
+  engine                  = "mariadb"
+  engine_version          = "10.1.14"
+  instance_class          = "db.t2.small" # use micro if you want to use the free tier
+  identifier              = "mariadb"
+  name                    = "mariadb"
+  username                = "root"           # username
+  password                = var.RDS_PASSWORD # password
+  db_subnet_group_name    = aws_db_subnet_group.mariadb-subnet.name
+  parameter_group_name    = aws_db_parameter_group.mariadb-parameters.name
+  multi_az                = "false" # set to true to have high availability: 2 instances synchronized with each other
+  vpc_security_group_ids  = [aws_security_group.allow-mariadb.id]
+  storage_type            = "gp2"
+  backup_retention_period = 30                                          # how long you’re going to keep your backups
+  availability_zone       = aws_subnet.main-private-1.availability_zone # prefered AZ
+  skip_final_snapshot     = true                                        # skip final snapshot when doing terraform destroy
+  tags = {
+    Name = "mariadb-instance"
+  }
+}
+
diff --git a/demo-12/securitygroup.tf b/demo-12/securitygroup.tf
index ab7eca5..ff881b3 100644
--- a/demo-12/securitygroup.tf
+++ b/demo-12/securitygroup.tf
@@ -1,43 +1,43 @@
 resource "aws_security_group" "example-instance" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-ssh"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "example-instance"
   }
 }
 
 resource "aws_security_group" "allow-mariadb" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-mariadb"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-mariadb"
   description = "allow-mariadb"
   ingress {
-      from_port = 3306
-      to_port = 3306
-      protocol = "tcp"
-      security_groups = ["${aws_security_group.example-instance.id}"]              # allowing access from our example instance
+    from_port       = 3306
+    to_port         = 3306
+    protocol        = "tcp"
+    security_groups = [aws_security_group.example-instance.id] # allowing access from our example instance
   }
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
-      self = true
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
+    self        = true
   }
-  tags {
+  tags = {
     Name = "allow-mariadb"
   }
 }
diff --git a/demo-12/vars.tf b/demo-12/vars.tf
index d4a15c5..0397cbb 100644
--- a/demo-12/vars.tf
+++ b/demo-12/vars.tf
@@ -1,18 +1,24 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
-variable "RDS_PASSWORD" { }
+
+variable "RDS_PASSWORD" {
+}
+
diff --git a/demo-12/versions.tf b/demo-12/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-12/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-12/vpc.tf b/demo-12/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-12/vpc.tf
+++ b/demo-12/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/demo-13/iam.tf b/demo-13/iam.tf
index fe6b296..2553895 100644
--- a/demo-13/iam.tf
+++ b/demo-13/iam.tf
@@ -1,28 +1,33 @@
 # group definition
 resource "aws_iam_group" "administrators" {
-    name = "administrators"
+  name = "administrators"
 }
+
 resource "aws_iam_policy_attachment" "administrators-attach" {
-    name = "administrators-attach"
-    groups = ["${aws_iam_group.administrators.name}"]
-    policy_arn = "arn:aws:iam::aws:policy/AdministratorAccess"
+  name       = "administrators-attach"
+  groups     = [aws_iam_group.administrators.name]
+  policy_arn = "arn:aws:iam::aws:policy/AdministratorAccess"
 }
+
 # user
 resource "aws_iam_user" "admin1" {
-    name = "admin1"
+  name = "admin1"
 }
+
 resource "aws_iam_user" "admin2" {
-    name = "admin2"
+  name = "admin2"
 }
+
 resource "aws_iam_group_membership" "administrators-users" {
-    name = "administrators-users"
-    users = [
-        "${aws_iam_user.admin1.name}",
-        "${aws_iam_user.admin2.name}",
-    ]
-    group = "${aws_iam_group.administrators.name}"
+  name = "administrators-users"
+  users = [
+    aws_iam_user.admin1.name,
+    aws_iam_user.admin2.name,
+  ]
+  group = aws_iam_group.administrators.name
 }
 
 output "warning" {
-    value = "WARNING: make sure you're not using the AdministratorAccess policy for other users/groups/roles. If this is the case, don't run terraform destroy, but manually unlink the created resources"
+  value = "WARNING: make sure you're not using the AdministratorAccess policy for other users/groups/roles. If this is the case, don't run terraform destroy, but manually unlink the created resources"
 }
+
diff --git a/demo-13/provider.tf b/demo-13/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-13/provider.tf
+++ b/demo-13/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-13/vars.tf b/demo-13/vars.tf
index 7c29d8c..ac7990c 100644
--- a/demo-13/vars.tf
+++ b/demo-13/vars.tf
@@ -1,3 +1,4 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
diff --git a/demo-13/versions.tf b/demo-13/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-13/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-14/iam.tf b/demo-14/iam.tf
index bf2f55b..32ce49a 100644
--- a/demo-14/iam.tf
+++ b/demo-14/iam.tf
@@ -1,6 +1,6 @@
 resource "aws_iam_role" "s3-mybucket-role" {
-    name = "s3-mybucket-role"
-    assume_role_policy = <<EOF
+  name               = "s3-mybucket-role"
+  assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -15,17 +15,18 @@ resource "aws_iam_role" "s3-mybucket-role" {
   ]
 }
 EOF
+
 }
 
 resource "aws_iam_instance_profile" "s3-mybucket-role-instanceprofile" {
-    name = "s3-mybucket-role"
-    role = "${aws_iam_role.s3-mybucket-role.name}"
+  name = "s3-mybucket-role"
+  role = aws_iam_role.s3-mybucket-role.name
 }
 
 resource "aws_iam_role_policy" "s3-mybucket-role-policy" {
-    name = "s3-mybucket-role-policy"
-    role = "${aws_iam_role.s3-mybucket-role.id}"
-    policy = <<EOF
+  name = "s3-mybucket-role-policy"
+  role = aws_iam_role.s3-mybucket-role.id
+  policy = <<EOF
 {
     "Version": "2012-10-17",
     "Statement": [
@@ -42,5 +43,6 @@ resource "aws_iam_role_policy" "s3-mybucket-role-policy" {
     ]
 }
 EOF
+
 }
 
diff --git a/demo-14/instance.tf b/demo-14/instance.tf
index 2e19649..d6fe5d4 100644
--- a/demo-14/instance.tf
+++ b/demo-14/instance.tf
@@ -1,17 +1,17 @@
 resource "aws_instance" "example" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.example-instance.id}"]
+  vpc_security_group_ids = [aws_security_group.example-instance.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 
   # role:
-  iam_instance_profile = "${aws_iam_instance_profile.s3-mybucket-role-instanceprofile.name}"
-
+  iam_instance_profile = aws_iam_instance_profile.s3-mybucket-role-instanceprofile.name
 }
+
diff --git a/demo-14/key.tf b/demo-14/key.tf
index 0d3c220..58b093f 100644
--- a/demo-14/key.tf
+++ b/demo-14/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/demo-14/output.tf b/demo-14/output.tf
index c95dddd..10cd449 100644
--- a/demo-14/output.tf
+++ b/demo-14/output.tf
@@ -1,3 +1,4 @@
 output "instance" {
-  value = "${aws_instance.example.public_ip}"
+  value = aws_instance.example.public_ip
 }
+
diff --git a/demo-14/provider.tf b/demo-14/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-14/provider.tf
+++ b/demo-14/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-14/s3.tf b/demo-14/s3.tf
index ce5f0c3..be32d4f 100644
--- a/demo-14/s3.tf
+++ b/demo-14/s3.tf
@@ -1,8 +1,9 @@
 resource "aws_s3_bucket" "b" {
-    bucket = "mybucket-c29df1"
-    acl = "private"
+  bucket = "mybucket-c29df1"
+  acl    = "private"
 
-    tags {
-        Name = "mybucket-c29df1"
-    }
+  tags = {
+    Name = "mybucket-c29df1"
+  }
 }
+
diff --git a/demo-14/securitygroup.tf b/demo-14/securitygroup.tf
index b796e18..fd476e9 100644
--- a/demo-14/securitygroup.tf
+++ b/demo-14/securitygroup.tf
@@ -1,21 +1,21 @@
 resource "aws_security_group" "example-instance" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-ssh"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "example-instance"
   }
 }
diff --git a/demo-14/vars.tf b/demo-14/vars.tf
index d880ef6..2712edf 100644
--- a/demo-14/vars.tf
+++ b/demo-14/vars.tf
@@ -1,17 +1,21 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-14/versions.tf b/demo-14/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-14/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-14/vpc.tf b/demo-14/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-14/vpc.tf
+++ b/demo-14/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/demo-15/autoscaling.tf b/demo-15/autoscaling.tf
index f71fbb8..f1acb9c 100644
--- a/demo-15/autoscaling.tf
+++ b/demo-15/autoscaling.tf
@@ -1,25 +1,25 @@
 resource "aws_launch_configuration" "example-launchconfig" {
-  name_prefix          = "example-launchconfig"
-  image_id             = "${lookup(var.AMIS, var.AWS_REGION)}"
-  instance_type        = "t2.micro"
-  key_name             = "${aws_key_pair.mykeypair.key_name}"
-  security_groups      = ["${aws_security_group.allow-ssh.id}"]
+  name_prefix     = "example-launchconfig"
+  image_id        = var.AMIS[var.AWS_REGION]
+  instance_type   = "t2.micro"
+  key_name        = aws_key_pair.mykeypair.key_name
+  security_groups = [aws_security_group.allow-ssh.id]
 }
 
 resource "aws_autoscaling_group" "example-autoscaling" {
-  name                 = "example-autoscaling"
-  vpc_zone_identifier  = ["${aws_subnet.main-public-1.id}", "${aws_subnet.main-public-2.id}"]
-  launch_configuration = "${aws_launch_configuration.example-launchconfig.name}"
-  min_size             = 1
-  max_size             = 2
+  name                      = "example-autoscaling"
+  vpc_zone_identifier       = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
+  launch_configuration      = aws_launch_configuration.example-launchconfig.name
+  min_size                  = 1
+  max_size                  = 2
   health_check_grace_period = 300
-  health_check_type = "EC2"
-  force_delete = true
+  health_check_type         = "EC2"
+  force_delete              = true
 
   tag {
-      key = "Name"
-      value = "ec2 instance"
-      propagate_at_launch = true
+    key                 = "Name"
+    value               = "ec2 instance"
+    propagate_at_launch = true
   }
 }
 
diff --git a/demo-15/autoscalingpolicy.tf b/demo-15/autoscalingpolicy.tf
index e095cd6..335992d 100644
--- a/demo-15/autoscalingpolicy.tf
+++ b/demo-15/autoscalingpolicy.tf
@@ -2,7 +2,7 @@
 
 resource "aws_autoscaling_policy" "example-cpu-policy" {
   name                   = "example-cpu-policy"
-  autoscaling_group_name = "${aws_autoscaling_group.example-autoscaling.name}"
+  autoscaling_group_name = aws_autoscaling_group.example-autoscaling.name
   adjustment_type        = "ChangeInCapacity"
   scaling_adjustment     = "1"
   cooldown               = "300"
@@ -21,17 +21,17 @@ resource "aws_cloudwatch_metric_alarm" "example-cpu-alarm" {
   threshold           = "30"
 
   dimensions = {
-    "AutoScalingGroupName" = "${aws_autoscaling_group.example-autoscaling.name}"
+    "AutoScalingGroupName" = aws_autoscaling_group.example-autoscaling.name
   }
 
   actions_enabled = true
-  alarm_actions   = ["${aws_autoscaling_policy.example-cpu-policy.arn}"]
+  alarm_actions   = [aws_autoscaling_policy.example-cpu-policy.arn]
 }
 
 # scale down alarm
 resource "aws_autoscaling_policy" "example-cpu-policy-scaledown" {
   name                   = "example-cpu-policy-scaledown"
-  autoscaling_group_name = "${aws_autoscaling_group.example-autoscaling.name}"
+  autoscaling_group_name = aws_autoscaling_group.example-autoscaling.name
   adjustment_type        = "ChangeInCapacity"
   scaling_adjustment     = "-1"
   cooldown               = "300"
@@ -50,9 +50,10 @@ resource "aws_cloudwatch_metric_alarm" "example-cpu-alarm-scaledown" {
   threshold           = "5"
 
   dimensions = {
-    "AutoScalingGroupName" = "${aws_autoscaling_group.example-autoscaling.name}"
+    "AutoScalingGroupName" = aws_autoscaling_group.example-autoscaling.name
   }
 
   actions_enabled = true
-  alarm_actions   = ["${aws_autoscaling_policy.example-cpu-policy-scaledown.arn}"]
+  alarm_actions   = [aws_autoscaling_policy.example-cpu-policy-scaledown.arn]
 }
+
diff --git a/demo-15/key.tf b/demo-15/key.tf
index 278a5a9..b41e059 100644
--- a/demo-15/key.tf
+++ b/demo-15/key.tf
@@ -1,7 +1,8 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
   lifecycle {
-    ignore_changes = ["public_key"]
+    ignore_changes = [public_key]
   }
 }
+
diff --git a/demo-15/provider.tf b/demo-15/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-15/provider.tf
+++ b/demo-15/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-15/securitygroup.tf b/demo-15/securitygroup.tf
index 05c0e12..1ec204b 100644
--- a/demo-15/securitygroup.tf
+++ b/demo-15/securitygroup.tf
@@ -1,21 +1,22 @@
 resource "aws_security_group" "allow-ssh" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-ssh"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "allow-ssh"
   }
 }
+
diff --git a/demo-15/sns.tf b/demo-15/sns.tf
index 6412e4c..82afd7a 100644
--- a/demo-15/sns.tf
+++ b/demo-15/sns.tf
@@ -1,5 +1,4 @@
 # Uncomment if you want to have autoscaling notifications
-
 #resource "aws_sns_topic" "example-sns" {
 #  name         = "sg-sns"
 #  display_name = "example ASG SNS topic"
diff --git a/demo-15/vars.tf b/demo-15/vars.tf
index d880ef6..2712edf 100644
--- a/demo-15/vars.tf
+++ b/demo-15/vars.tf
@@ -1,17 +1,21 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-15/versions.tf b/demo-15/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-15/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-15/vpc.tf b/demo-15/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-15/vpc.tf
+++ b/demo-15/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/demo-16/autoscaling.tf b/demo-16/autoscaling.tf
index 00ed282..6d2047b 100644
--- a/demo-16/autoscaling.tf
+++ b/demo-16/autoscaling.tf
@@ -1,28 +1,30 @@
 resource "aws_launch_configuration" "example-launchconfig" {
-  name_prefix          = "example-launchconfig"
-  image_id             = "${lookup(var.AMIS, var.AWS_REGION)}"
-  instance_type        = "t2.micro"
-  key_name             = "${aws_key_pair.mykeypair.key_name}"
-  security_groups      = ["${aws_security_group.myinstance.id}"]
-  user_data            = "#!/bin/bash\napt-get update\napt-get -y install nginx\nMYIP=`ifconfig | grep 'addr:10' | awk '{ print $2 }' | cut -d ':' -f2`\necho 'this is: '$MYIP > /var/www/html/index.html"
-  lifecycle              { create_before_destroy = true }
-}
-
-resource "aws_autoscaling_group" "example-autoscaling" {
-  name                 = "example-autoscaling"
-  vpc_zone_identifier  = ["${aws_subnet.main-public-1.id}", "${aws_subnet.main-public-2.id}"]
-  launch_configuration = "${aws_launch_configuration.example-launchconfig.name}"
-  min_size             = 2
-  max_size             = 2
-  health_check_grace_period = 300
-  health_check_type = "ELB"
-  load_balancers = ["${aws_elb.my-elb.name}"]
-  force_delete = true
-
-  tag {
-      key = "Name"
-      value = "ec2 instance"
-      propagate_at_launch = true
+  name_prefix     = "example-launchconfig"
+  image_id        = var.AMIS[var.AWS_REGION]
+  instance_type   = "t2.micro"
+  key_name        = aws_key_pair.mykeypair.key_name
+  security_groups = [aws_security_group.myinstance.id]
+  user_data       = "#!/bin/bash\napt-get update\napt-get -y install nginx\nMYIP=`ifconfig | grep 'addr:10' | awk '{ print $2 }' | cut -d ':' -f2`\necho 'this is: '$MYIP > /var/www/html/index.html"
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "aws_autoscaling_group" "example-autoscaling" {
+  name                      = "example-autoscaling"
+  vpc_zone_identifier       = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
+  launch_configuration      = aws_launch_configuration.example-launchconfig.name
+  min_size                  = 2
+  max_size                  = 2
+  health_check_grace_period = 300
+  health_check_type         = "ELB"
+  load_balancers            = [aws_elb.my-elb.name]
+  force_delete              = true
+
+  tag {
+    key                 = "Name"
+    value               = "ec2 instance"
+    propagate_at_launch = true
   }
 }
 
diff --git a/demo-16/elb.tf b/demo-16/elb.tf
index 5c0d870..dc0c23e 100644
--- a/demo-16/elb.tf
+++ b/demo-16/elb.tf
@@ -1,25 +1,25 @@
 resource "aws_elb" "my-elb" {
-  name = "my-elb"
-  subnets = ["${aws_subnet.main-public-1.id}", "${aws_subnet.main-public-2.id}"]
-  security_groups = ["${aws_security_group.elb-securitygroup.id}"]
- listener {
-    instance_port = 80
+  name            = "my-elb"
+  subnets         = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
+  security_groups = [aws_security_group.elb-securitygroup.id]
+  listener {
+    instance_port     = 80
     instance_protocol = "http"
-    lb_port = 80
-    lb_protocol = "http"
+    lb_port           = 80
+    lb_protocol       = "http"
   }
   health_check {
-    healthy_threshold = 2
+    healthy_threshold   = 2
     unhealthy_threshold = 2
-    timeout = 3
-    target = "HTTP:80/"
-    interval = 30
+    timeout             = 3
+    target              = "HTTP:80/"
+    interval            = 30
   }
 
-  cross_zone_load_balancing = true
-  connection_draining = true
+  cross_zone_load_balancing   = true
+  connection_draining         = true
   connection_draining_timeout = 400
-  tags {
+  tags = {
     Name = "my-elb"
   }
 }
diff --git a/demo-16/key.tf b/demo-16/key.tf
index 278a5a9..b41e059 100644
--- a/demo-16/key.tf
+++ b/demo-16/key.tf
@@ -1,7 +1,8 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
   lifecycle {
-    ignore_changes = ["public_key"]
+    ignore_changes = [public_key]
   }
 }
+
diff --git a/demo-16/output.tf b/demo-16/output.tf
index 64d93d6..2df9d23 100644
--- a/demo-16/output.tf
+++ b/demo-16/output.tf
@@ -1,3 +1,4 @@
 output "ELB" {
-	value = "${aws_elb.my-elb.dns_name}"
+  value = aws_elb.my-elb.dns_name
 }
+
diff --git a/demo-16/provider.tf b/demo-16/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-16/provider.tf
+++ b/demo-16/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-16/securitygroup.tf b/demo-16/securitygroup.tf
index ee678c6..e6b24b6 100644
--- a/demo-16/securitygroup.tf
+++ b/demo-16/securitygroup.tf
@@ -1,50 +1,52 @@
 resource "aws_security_group" "myinstance" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "myinstance"
+  vpc_id      = aws_vpc.main.id
+  name        = "myinstance"
   description = "security group for my instance"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-
-  ingress {
-      from_port = 80
-      to_port = 80
-      protocol = "tcp"
-      security_groups = ["${aws_security_group.elb-securitygroup.id}"]
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
-  tags {
+  ingress {
+    from_port       = 80
+    to_port         = 80
+    protocol        = "tcp"
+    security_groups = [aws_security_group.elb-securitygroup.id]
+  }
+
+  tags = {
     Name = "myinstance"
   }
 }
+
 resource "aws_security_group" "elb-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "elb"
+  vpc_id      = aws_vpc.main.id
+  name        = "elb"
   description = "security group for load balancer"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 80
-      to_port = 80
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-  tags {
+    from_port   = 80
+    to_port     = 80
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "elb"
   }
 }
+
diff --git a/demo-16/vars.tf b/demo-16/vars.tf
index d880ef6..2712edf 100644
--- a/demo-16/vars.tf
+++ b/demo-16/vars.tf
@@ -1,17 +1,21 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-16/versions.tf b/demo-16/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-16/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-16/vpc.tf b/demo-16/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-16/vpc.tf
+++ b/demo-16/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/demo-17/elasticbeanstalk.tf b/demo-17/elasticbeanstalk.tf
index 8b545d8..db24788 100644
--- a/demo-17/elasticbeanstalk.tf
+++ b/demo-17/elasticbeanstalk.tf
@@ -1,112 +1,111 @@
 resource "aws_elastic_beanstalk_application" "app" {
-  name = "app"
+  name        = "app"
   description = "app"
 }
 
 resource "aws_elastic_beanstalk_environment" "app-prod" {
-  name = "app-prod"
-  application = "${aws_elastic_beanstalk_application.app.name}"
+  name                = "app-prod"
+  application         = aws_elastic_beanstalk_application.app.name
   solution_stack_name = "64bit Amazon Linux 2016.09 v2.3.0 running PHP 7.0"
   setting {
     namespace = "aws:ec2:vpc"
     name      = "VPCId"
-    value     = "${aws_vpc.main.id}"
+    value     = aws_vpc.main.id
   }
   setting {
     namespace = "aws:ec2:vpc"
-    name = "Subnets"
-    value = "${aws_subnet.main-private-1.id},${aws_subnet.main-private-2.id}"
+    name      = "Subnets"
+    value     = "${aws_subnet.main-private-1.id},${aws_subnet.main-private-2.id}"
   }
   setting {
     namespace = "aws:ec2:vpc"
-    name = "AssociatePublicIpAddress"
-    value = "false"
+    name      = "AssociatePublicIpAddress"
+    value     = "false"
   }
   setting {
     namespace = "aws:autoscaling:launchconfiguration"
-    name = "IamInstanceProfile"
-    value = "${aws_iam_instance_profile.app-ec2-role.name}"
+    name      = "IamInstanceProfile"
+    value     = aws_iam_instance_profile.app-ec2-role.name
   }
   setting {
     namespace = "aws:autoscaling:launchconfiguration"
-    name = "SecurityGroups"
-    value = "${aws_security_group.app-prod.id}"
+    name      = "SecurityGroups"
+    value     = aws_security_group.app-prod.id
   }
   setting {
     namespace = "aws:autoscaling:launchconfiguration"
-    name = "EC2KeyName"
-    value = "${aws_key_pair.mykeypair.id}"
+    name      = "EC2KeyName"
+    value     = aws_key_pair.mykeypair.id
   }
   setting {
     namespace = "aws:autoscaling:launchconfiguration"
-    name = "InstanceType"
-    value = "t2.micro"
+    name      = "InstanceType"
+    value     = "t2.micro"
   }
   setting {
     namespace = "aws:elasticbeanstalk:environment"
-    name = "ServiceRole"
-    value = "${aws_iam_role.elasticbeanstalk-service-role.name}"
+    name      = "ServiceRole"
+    value     = aws_iam_role.elasticbeanstalk-service-role.name
   }
   setting {
     namespace = "aws:ec2:vpc"
-    name = "ELBScheme"
-    value = "public"
+    name      = "ELBScheme"
+    value     = "public"
   }
   setting {
     namespace = "aws:ec2:vpc"
-    name = "ELBSubnets"
-    value = "${aws_subnet.main-public-1.id},${aws_subnet.main-public-2.id}"
+    name      = "ELBSubnets"
+    value     = "${aws_subnet.main-public-1.id},${aws_subnet.main-public-2.id}"
   }
   setting {
     namespace = "aws:elb:loadbalancer"
-    name = "CrossZone"
-    value = "true"
+    name      = "CrossZone"
+    value     = "true"
   }
   setting {
     namespace = "aws:elasticbeanstalk:command"
-    name = "BatchSize"
-    value = "30"
+    name      = "BatchSize"
+    value     = "30"
   }
   setting {
     namespace = "aws:elasticbeanstalk:command"
-    name = "BatchSizeType"
-    value = "Percentage"
+    name      = "BatchSizeType"
+    value     = "Percentage"
   }
   setting {
     namespace = "aws:autoscaling:asg"
-    name = "Availability Zones"
-    value = "Any 2"
+    name      = "Availability Zones"
+    value     = "Any 2"
   }
   setting {
     namespace = "aws:autoscaling:asg"
-    name = "MinSize"
-    value = "1"
+    name      = "MinSize"
+    value     = "1"
   }
   setting {
     namespace = "aws:autoscaling:updatepolicy:rollingupdate"
-    name = "RollingUpdateType"
-    value = "Health"
+    name      = "RollingUpdateType"
+    value     = "Health"
   }
   setting {
     namespace = "aws:elasticbeanstalk:application:environment"
-    name = "RDS_USERNAME"
-    value = "${aws_db_instance.mariadb.username}"
+    name      = "RDS_USERNAME"
+    value     = aws_db_instance.mariadb.username
   }
   setting {
     namespace = "aws:elasticbeanstalk:application:environment"
-    name = "RDS_PASSWORD"
-    value = "${aws_db_instance.mariadb.password}"
+    name      = "RDS_PASSWORD"
+    value     = aws_db_instance.mariadb.password
   }
   setting {
     namespace = "aws:elasticbeanstalk:application:environment"
-    name = "RDS_DATABASE"
-    value = "mydb"
-    value = "${aws_db_instance.mariadb.name}"
+    name      = "RDS_DATABASE"
+    value     = aws_db_instance.mariadb.name
   }
   setting {
     namespace = "aws:elasticbeanstalk:application:environment"
-    name = "RDS_HOSTNAME"
-    value = "${aws_db_instance.mariadb.endpoint}"
+    name      = "RDS_HOSTNAME"
+    value     = aws_db_instance.mariadb.endpoint
   }
 }
 
diff --git a/demo-17/iam.tf b/demo-17/iam.tf
index c500b42..48f64c6 100644
--- a/demo-17/iam.tf
+++ b/demo-17/iam.tf
@@ -1,7 +1,7 @@
 # iam roles
 resource "aws_iam_role" "app-ec2-role" {
-    name = "app-ec2-role"
-    assume_role_policy = <<EOF
+  name               = "app-ec2-role"
+  assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -16,16 +16,18 @@ resource "aws_iam_role" "app-ec2-role" {
   ]
 }
 EOF
+
 }
+
 resource "aws_iam_instance_profile" "app-ec2-role" {
-    name = "app-ec2-role"
-    role = "${aws_iam_role.app-ec2-role.name}"
+  name = "app-ec2-role"
+  role = aws_iam_role.app-ec2-role.name
 }
 
 # service
 resource "aws_iam_role" "elasticbeanstalk-service-role" {
-    name = "elasticbeanstalk-service-role"
-    assume_role_policy = <<EOF
+  name = "elasticbeanstalk-service-role"
+  assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -40,26 +42,31 @@ resource "aws_iam_role" "elasticbeanstalk-service-role" {
   ]
 }
 EOF
+
 }
 
 # policies
 resource "aws_iam_policy_attachment" "app-attach1" {
-    name = "app-attach1"
-    roles = ["${aws_iam_role.app-ec2-role.name}"]
-    policy_arn = "arn:aws:iam::aws:policy/AWSElasticBeanstalkWebTier"
+name       = "app-attach1"
+roles      = [aws_iam_role.app-ec2-role.name]
+policy_arn = "arn:aws:iam::aws:policy/AWSElasticBeanstalkWebTier"
 }
+
 resource "aws_iam_policy_attachment" "app-attach2" {
-    name = "app-attach2"
-    roles = ["${aws_iam_role.app-ec2-role.name}"]
-    policy_arn = "arn:aws:iam::aws:policy/AWSElasticBeanstalkMulticontainerDocker"
+name       = "app-attach2"
+roles      = [aws_iam_role.app-ec2-role.name]
+policy_arn = "arn:aws:iam::aws:policy/AWSElasticBeanstalkMulticontainerDocker"
 }
+
 resource "aws_iam_policy_attachment" "app-attach3" {
-    name = "app-attach3"
-    roles = ["${aws_iam_role.app-ec2-role.name}"]
-    policy_arn = "arn:aws:iam::aws:policy/AWSElasticBeanstalkWorkerTier"
+name       = "app-attach3"
+roles      = [aws_iam_role.app-ec2-role.name]
+policy_arn = "arn:aws:iam::aws:policy/AWSElasticBeanstalkWorkerTier"
 }
+
 resource "aws_iam_policy_attachment" "app-attach4" {
-    name = "app-attach4"
-    roles = ["${aws_iam_role.elasticbeanstalk-service-role.name}"]
-    policy_arn = "arn:aws:iam::aws:policy/service-role/AWSElasticBeanstalkEnhancedHealth"
+name       = "app-attach4"
+roles      = [aws_iam_role.elasticbeanstalk-service-role.name]
+policy_arn = "arn:aws:iam::aws:policy/service-role/AWSElasticBeanstalkEnhancedHealth"
 }
+
diff --git a/demo-17/key.tf b/demo-17/key.tf
index 278a5a9..b41e059 100644
--- a/demo-17/key.tf
+++ b/demo-17/key.tf
@@ -1,7 +1,8 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
   lifecycle {
-    ignore_changes = ["public_key"]
+    ignore_changes = [public_key]
   }
 }
+
diff --git a/demo-17/output.tf b/demo-17/output.tf
index 18ee1cd..b1825e0 100644
--- a/demo-17/output.tf
+++ b/demo-17/output.tf
@@ -1,3 +1,4 @@
 output "eb" {
-	value = "${aws_elastic_beanstalk_environment.app-prod.cname}"
+  value = aws_elastic_beanstalk_environment.app-prod.cname
 }
+
diff --git a/demo-17/provider.tf b/demo-17/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-17/provider.tf
+++ b/demo-17/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-17/rds.tf b/demo-17/rds.tf
index 89e7ec9..a98519c 100644
--- a/demo-17/rds.tf
+++ b/demo-17/rds.tf
@@ -1,40 +1,39 @@
 resource "aws_db_subnet_group" "mariadb-subnet" {
-    name = "mariadb-subnet"
-    description = "RDS subnet group"
-    subnet_ids = ["${aws_subnet.main-private-1.id}","${aws_subnet.main-private-2.id}"]
+  name        = "mariadb-subnet"
+  description = "RDS subnet group"
+  subnet_ids  = [aws_subnet.main-private-1.id, aws_subnet.main-private-2.id]
 }
 
 resource "aws_db_parameter_group" "mariadb-parameters" {
-    name = "mariadb-params"
-    family = "mariadb10.1"
-    description = "MariaDB parameter group"
+  name        = "mariadb-params"
+  family      = "mariadb10.1"
+  description = "MariaDB parameter group"
 
-    parameter {
-      name = "max_allowed_packet"
-      value = "16777216"
-   }
-
-}
-
-
-resource "aws_db_instance" "mariadb" {
-  allocated_storage    = 100    # 100 GB of storage, gives us more IOPS than a lower number
-  engine               = "mariadb"
-  engine_version       = "10.1.14"
-  instance_class       = "db.t2.small"    # use micro if you want to use the free tier
-  identifier           = "mariadb"
-  name                 = "mydatabase" # database name
-  username             = "root"   # username
-  password             = "${var.RDS_PASSWORD}" # password
-  db_subnet_group_name = "${aws_db_subnet_group.mariadb-subnet.name}"
-  parameter_group_name = "${aws_db_parameter_group.mariadb-parameters.name}"
-  multi_az             = "false"     # set to true to have high availability: 2 instances synchronized with each other
-  vpc_security_group_ids = ["${aws_security_group.allow-mariadb.id}"]
-  storage_type         = "gp2"
-  backup_retention_period = 30    # how long you’re going to keep your backups
-  availability_zone = "${aws_subnet.main-private-1.availability_zone}"   # prefered AZ
-  final_snapshot_identifier = "mariadb-final-snapshot" # final snapshot when executing terraform destroy
-  tags {
-      Name = "mariadb-instance"
+  parameter {
+    name  = "max_allowed_packet"
+    value = "16777216"
   }
 }
+
+resource "aws_db_instance" "mariadb" {
+  allocated_storage         = 100 # 100 GB of storage, gives us more IOPS than a lower number
+  engine                    = "mariadb"
+  engine_version            = "10.1.14"
+  instance_class            = "db.t2.small" # use micro if you want to use the free tier
+  identifier                = "mariadb"
+  name                      = "mydatabase"     # database name
+  username                  = "root"           # username
+  password                  = var.RDS_PASSWORD # password
+  db_subnet_group_name      = aws_db_subnet_group.mariadb-subnet.name
+  parameter_group_name      = aws_db_parameter_group.mariadb-parameters.name
+  multi_az                  = "false" # set to true to have high availability: 2 instances synchronized with each other
+  vpc_security_group_ids    = [aws_security_group.allow-mariadb.id]
+  storage_type              = "gp2"
+  backup_retention_period   = 30                                          # how long you’re going to keep your backups
+  availability_zone         = aws_subnet.main-private-1.availability_zone # prefered AZ
+  final_snapshot_identifier = "mariadb-final-snapshot"                    # final snapshot when executing terraform destroy
+  tags = {
+    Name = "mariadb-instance"
+  }
+}
+
diff --git a/demo-17/securitygroup.tf b/demo-17/securitygroup.tf
index 84b4c7c..88858b9 100644
--- a/demo-17/securitygroup.tf
+++ b/demo-17/securitygroup.tf
@@ -1,44 +1,45 @@
 resource "aws_security_group" "app-prod" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "application - production"
+  vpc_id      = aws_vpc.main.id
+  name        = "application - production"
   description = "security group for my app"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
 
-
-  tags {
+  tags = {
     Name = "myinstance"
   }
 }
+
 resource "aws_security_group" "allow-mariadb" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-mariadb"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-mariadb"
   description = "allow-mariadb"
   ingress {
-      from_port = 3306
-      to_port = 3306
-      protocol = "tcp"
-      security_groups = ["${aws_security_group.app-prod.id}"]              # allowing access from our example instance
+    from_port       = 3306
+    to_port         = 3306
+    protocol        = "tcp"
+    security_groups = [aws_security_group.app-prod.id] # allowing access from our example instance
   }
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
-      self = true
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
+    self        = true
   }
-  tags {
+  tags = {
     Name = "allow-mariadb"
   }
 }
+
diff --git a/demo-17/vars.tf b/demo-17/vars.tf
index 5dfe95e..a525c2e 100644
--- a/demo-17/vars.tf
+++ b/demo-17/vars.tf
@@ -1,10 +1,15 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
-variable "RDS_PASSWORD" {}
+
+variable "RDS_PASSWORD" {
+}
+
diff --git a/demo-17/versions.tf b/demo-17/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-17/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-17/vpc.tf b/demo-17/vpc.tf
index 89e4700..186c599 100644
--- a/demo-17/vpc.tf
+++ b/demo-17/vpc.tf
@@ -1,143 +1,156 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
-resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
-}
-resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
-}
-resource "aws_route_table" "main-private" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        nat_gateway_id = "${aws_nat_gateway.nat-gw.id}"
-    }
 
-    tags {
-        Name = "main-private-1"
-    }
+resource "aws_route_table_association" "main-public-2-a" {
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
+resource "aws_route_table_association" "main-public-3-a" {
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
+}
+
+resource "aws_route_table" "main-private" {
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block     = "0.0.0.0/0"
+    nat_gateway_id = aws_nat_gateway.nat-gw.id
+  }
+
+  tags = {
+    Name = "main-private-1"
+  }
+}
+
 # route associations private
 resource "aws_route_table_association" "main-private-1-a" {
-    subnet_id = "${aws_subnet.main-private-1.id}"
-    route_table_id = "${aws_route_table.main-private.id}"
+  subnet_id      = aws_subnet.main-private-1.id
+  route_table_id = aws_route_table.main-private.id
 }
+
 resource "aws_route_table_association" "main-private-2-a" {
-    subnet_id = "${aws_subnet.main-private-2.id}"
-    route_table_id = "${aws_route_table.main-private.id}"
+  subnet_id      = aws_subnet.main-private-2.id
+  route_table_id = aws_route_table.main-private.id
 }
+
 resource "aws_route_table_association" "main-private-3-a" {
-    subnet_id = "${aws_subnet.main-private-3.id}"
-    route_table_id = "${aws_route_table.main-private.id}"
+  subnet_id      = aws_subnet.main-private-3.id
+  route_table_id = aws_route_table.main-private.id
 }
+
 # nat gw
 resource "aws_eip" "nat" {
-  vpc      = true
+  vpc = true
 }
+
 resource "aws_nat_gateway" "nat-gw" {
-  allocation_id = "${aws_eip.nat.id}"
-  subnet_id = "${aws_subnet.main-public-1.id}"
-  depends_on = ["aws_internet_gateway.main-gw"]
+  allocation_id = aws_eip.nat.id
+  subnet_id     = aws_subnet.main-public-1.id
+  depends_on    = [aws_internet_gateway.main-gw]
 }
+
diff --git a/demo-18/instance.tf b/demo-18/instance.tf
index 135388d..a2a6968 100644
--- a/demo-18/instance.tf
+++ b/demo-18/instance.tf
@@ -15,15 +15,16 @@ data "aws_ami" "ubuntu" {
 }
 
 resource "aws_instance" "example" {
-  ami           = "${data.aws_ami.ubuntu.id}"
+  ami           = data.aws_ami.ubuntu.id
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${var.ENV == "prod" ? module.vpc-prod.public_subnets[0] : module.vpc-dev.public_subnets[0] }"
+  subnet_id = var.ENV == "prod" ? module.vpc-prod.public_subnets[0] : module.vpc-dev.public_subnets[0]
 
   # the security group
-  vpc_security_group_ids = ["${var.ENV == "prod" ? aws_security_group.allow-ssh-prod.id : aws_security_group.allow-ssh-dev.id }"]
+  vpc_security_group_ids = [var.ENV == "prod" ? aws_security_group.allow-ssh-prod.id : aws_security_group.allow-ssh-dev.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 }
+
diff --git a/demo-18/key.tf b/demo-18/key.tf
index 2b92f43..58b093f 100644
--- a/demo-18/key.tf
+++ b/demo-18/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
   key_name   = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/demo-18/provider.tf b/demo-18/provider.tf
index 5606109..7925c73 100644
--- a/demo-18/provider.tf
+++ b/demo-18/provider.tf
@@ -1,3 +1,4 @@
 provider "aws" {
-  region  = "${var.AWS_REGION}"
+  region = var.AWS_REGION
 }
+
diff --git a/demo-18/securitygroup.tf b/demo-18/securitygroup.tf
index 6509648..8091a4f 100644
--- a/demo-18/securitygroup.tf
+++ b/demo-18/securitygroup.tf
@@ -1,5 +1,5 @@
 resource "aws_security_group" "allow-ssh-prod" {
-  vpc_id      = "${module.vpc-prod.vpc_id}"
+  vpc_id      = module.vpc-prod.vpc_id
   name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
 
@@ -17,13 +17,13 @@ resource "aws_security_group" "allow-ssh-prod" {
     cidr_blocks = ["0.0.0.0/0"]
   }
 
-  tags {
+  tags = {
     Name = "allow-ssh"
   }
 }
 
 resource "aws_security_group" "allow-ssh-dev" {
-  vpc_id      = "${module.vpc-dev.vpc_id}"
+  vpc_id      = module.vpc-dev.vpc_id
   name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
 
@@ -41,7 +41,8 @@ resource "aws_security_group" "allow-ssh-dev" {
     cidr_blocks = ["0.0.0.0/0"]
   }
 
-  tags {
+  tags = {
     Name = "allow-ssh"
   }
 }
+
diff --git a/demo-18/vars.tf b/demo-18/vars.tf
index d89ef11..5299912 100644
--- a/demo-18/vars.tf
+++ b/demo-18/vars.tf
@@ -13,3 +13,4 @@ variable "PATH_TO_PUBLIC_KEY" {
 variable "ENV" {
   default = "prod"
 }
+
diff --git a/demo-18/versions.tf b/demo-18/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-18/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-18/vpc.tf b/demo-18/vpc.tf
index b25704a..b36d10e 100644
--- a/demo-18/vpc.tf
+++ b/demo-18/vpc.tf
@@ -1,5 +1,6 @@
 module "vpc-prod" {
-  source = "terraform-aws-modules/vpc/aws"
+  source  = "terraform-aws-modules/vpc/aws"
+  version = "2.5.0"
 
   name = "vpc-prod"
   cidr = "10.0.0.0/16"
@@ -18,7 +19,8 @@ module "vpc-prod" {
 }
 
 module "vpc-dev" {
-  source = "terraform-aws-modules/vpc/aws"
+  source  = "terraform-aws-modules/vpc/aws"
+  version = "2.5.0"
 
   name = "vpc-dev"
   cidr = "10.0.0.0/16"
@@ -35,3 +37,4 @@ module "vpc-dev" {
     Environment = "dev"
   }
 }
+
diff --git a/demo-18b/dev/dev.tf b/demo-18b/dev/dev.tf
index 728b1d0..5a03751 100644
--- a/demo-18b/dev/dev.tf
+++ b/demo-18b/dev/dev.tf
@@ -1,12 +1,13 @@
 module "main-vpc" {
-  source = "../modules/vpc"
-  ENV = "dev"
-  AWS_REGION = "${var.AWS_REGION}"
+  source     = "../modules/vpc"
+  ENV        = "dev"
+  AWS_REGION = var.AWS_REGION
 }
 
 module "instances" {
-  source = "../modules/instances"
-  ENV = "dev"
-  VPC_ID = "${module.main-vpc.vpc_id}"
-  PUBLIC_SUBNETS = ["${module.main-vpc.public_subnets}"]
+  source         = "../modules/instances"
+  ENV            = "dev"
+  VPC_ID         = module.main-vpc.vpc_id
+  PUBLIC_SUBNETS = module.main-vpc.public_subnets
 }
+
diff --git a/demo-18b/dev/provider.tf b/demo-18b/dev/provider.tf
index 5606109..7925c73 100644
--- a/demo-18b/dev/provider.tf
+++ b/demo-18b/dev/provider.tf
@@ -1,3 +1,4 @@
 provider "aws" {
-  region  = "${var.AWS_REGION}"
+  region = var.AWS_REGION
 }
+
diff --git a/demo-18b/dev/vars.tf b/demo-18b/dev/vars.tf
index 7c29d8c..ac7990c 100644
--- a/demo-18b/dev/vars.tf
+++ b/demo-18b/dev/vars.tf
@@ -1,3 +1,4 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
diff --git a/demo-18b/dev/versions.tf b/demo-18b/dev/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-18b/dev/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-18b/modules/instances/instance.tf b/demo-18b/modules/instances/instance.tf
index e2b9f8c..c53488a 100644
--- a/demo-18b/modules/instances/instance.tf
+++ b/demo-18b/modules/instances/instance.tf
@@ -1,14 +1,16 @@
-variable "ENV" {}
+variable "ENV" {
+}
 
 variable "INSTANCE_TYPE" {
   default = "t2.micro"
 }
 
 variable "PUBLIC_SUBNETS" {
-  type = "list"
+  type = list
 }
 
-variable "VPC_ID" {}
+variable "VPC_ID" {
+}
 
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
@@ -31,26 +33,26 @@ data "aws_ami" "ubuntu" {
 }
 
 resource "aws_instance" "instance" {
-  ami           = "${data.aws_ami.ubuntu.id}"
-  instance_type = "${var.INSTANCE_TYPE}"
+  ami           = data.aws_ami.ubuntu.id
+  instance_type = var.INSTANCE_TYPE
 
   # the VPC subnet
-  subnet_id = "${var.PUBLIC_SUBNETS[0]}"
+  subnet_id = element(var.PUBLIC_SUBNETS, 0)
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.allow-ssh.id}"]
+  vpc_security_group_ids = [aws_security_group.allow-ssh.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 
-  tags {
+  tags = {
     Name         = "instance-${var.ENV}"
-    Environmnent = "${var.ENV}"
+    Environmnent = var.ENV
   }
 }
 
 resource "aws_security_group" "allow-ssh" {
-  vpc_id      = "${var.VPC_ID}"
+  vpc_id      = var.VPC_ID
   name        = "allow-ssh-${var.ENV}"
   description = "security group that allows ssh and all egress traffic"
 
@@ -68,13 +70,14 @@ resource "aws_security_group" "allow-ssh" {
     cidr_blocks = ["0.0.0.0/0"]
   }
 
-  tags {
+  tags = {
     Name         = "allow-ssh"
-    Environmnent = "${var.ENV}"
+    Environmnent = var.ENV
   }
 }
 
 resource "aws_key_pair" "mykeypair" {
   key_name   = "mykeypair-${var.ENV}"
-  public_key = "${file("${path.root}/${var.PATH_TO_PUBLIC_KEY}")}"
+  public_key = file("${path.root}/${var.PATH_TO_PUBLIC_KEY}")
 }
+
diff --git a/demo-18b/modules/instances/versions.tf b/demo-18b/modules/instances/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-18b/modules/instances/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-18b/modules/vpc/versions.tf b/demo-18b/modules/vpc/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-18b/modules/vpc/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-18b/modules/vpc/vpc.tf b/demo-18b/modules/vpc/vpc.tf
index 6b41839..2511795 100644
--- a/demo-18b/modules/vpc/vpc.tf
+++ b/demo-18b/modules/vpc/vpc.tf
@@ -1,5 +1,8 @@
-variable "ENV" {}
-variable "AWS_REGION" {}
+variable "ENV" {
+}
+
+variable "AWS_REGION" {
+}
 
 module "main-vpc" {
   source = "terraform-aws-modules/vpc/aws"
@@ -16,21 +19,22 @@ module "main-vpc" {
 
   tags = {
     Terraform   = "true"
-    Environment = "${var.ENV}"
+    Environment = var.ENV
   }
 }
 
 output "vpc_id" {
   description = "The ID of the VPC"
-  value       = "${module.main-vpc.vpc_id}"
+  value       = module.main-vpc.vpc_id
 }
 
 output "private_subnets" {
   description = "List of IDs of private subnets"
-  value       = ["${module.main-vpc.private_subnets}"]
+  value       = module.main-vpc.private_subnets
 }
 
 output "public_subnets" {
   description = "List of IDs of public subnets"
-  value       = ["${module.main-vpc.public_subnets}"]
+  value       = module.main-vpc.public_subnets
 }
+
diff --git a/demo-18b/prod/prod.tf b/demo-18b/prod/prod.tf
index d12b5cf..0b2cf93 100644
--- a/demo-18b/prod/prod.tf
+++ b/demo-18b/prod/prod.tf
@@ -1,12 +1,13 @@
 module "main-vpc" {
-  source = "../modules/vpc"
-  ENV = "prod"
-  AWS_REGION = "${var.AWS_REGION}"
+  source     = "../modules/vpc"
+  ENV        = "prod"
+  AWS_REGION = var.AWS_REGION
 }
 
 module "instances" {
-  source = "../modules/instances"
-  ENV = "prod"
-  VPC_ID = "${module.main-vpc.vpc_id}"
-  PUBLIC_SUBNETS = ["${module.main-vpc.public_subnets}"]
+  source         = "../modules/instances"
+  ENV            = "prod"
+  VPC_ID         = module.main-vpc.vpc_id
+  PUBLIC_SUBNETS = module.main-vpc.public_subnets
 }
+
diff --git a/demo-18b/prod/provider.tf b/demo-18b/prod/provider.tf
index 5606109..7925c73 100644
--- a/demo-18b/prod/provider.tf
+++ b/demo-18b/prod/provider.tf
@@ -1,3 +1,4 @@
 provider "aws" {
-  region  = "${var.AWS_REGION}"
+  region = var.AWS_REGION
 }
+
diff --git a/demo-18b/prod/vars.tf b/demo-18b/prod/vars.tf
index 7c29d8c..ac7990c 100644
--- a/demo-18b/prod/vars.tf
+++ b/demo-18b/prod/vars.tf
@@ -1,3 +1,4 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
diff --git a/demo-18b/prod/versions.tf b/demo-18b/prod/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-18b/prod/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-2/instance.tf b/demo-2/instance.tf
index 97d1c21..097a29f 100644
--- a/demo-2/instance.tf
+++ b/demo-2/instance.tf
@@ -1,26 +1,28 @@
 resource "aws_key_pair" "mykey" {
-  key_name = "mykey"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykey"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
 
 resource "aws_instance" "example" {
-  ami = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
-  key_name = "${aws_key_pair.mykey.key_name}"
+  key_name      = aws_key_pair.mykey.key_name
 
   provisioner "file" {
-    source = "script.sh"
+    source      = "script.sh"
     destination = "/tmp/script.sh"
   }
   provisioner "remote-exec" {
     inline = [
       "chmod +x /tmp/script.sh",
-      "sudo /tmp/script.sh"
+      "sudo /tmp/script.sh",
     ]
   }
   connection {
-    host = "${self.public_ip}"
-    user = "${var.INSTANCE_USERNAME}"
-    private_key = "${file("${var.PATH_TO_PRIVATE_KEY}")}"
+    host        = coalesce(self.public_ip, self.private_ip)
+    type        = "ssh"
+    user        = var.INSTANCE_USERNAME
+    private_key = file(var.PATH_TO_PRIVATE_KEY)
   }
 }
+
diff --git a/demo-2/provider.tf b/demo-2/provider.tf
index 9f26b63..696b517 100644
--- a/demo-2/provider.tf
+++ b/demo-2/provider.tf
@@ -1,6 +1,6 @@
 provider "aws" {
-    access_key = "${var.AWS_ACCESS_KEY}"
-    secret_key = "${var.AWS_SECRET_KEY}"
-    region = "${var.AWS_REGION}"
+  access_key = var.AWS_ACCESS_KEY
+  secret_key = var.AWS_SECRET_KEY
+  region     = var.AWS_REGION
 }
 
diff --git a/demo-2/vars.tf b/demo-2/vars.tf
index 6ce0623..d8ee79b 100644
--- a/demo-2/vars.tf
+++ b/demo-2/vars.tf
@@ -1,10 +1,15 @@
-variable "AWS_ACCESS_KEY" {}
-variable "AWS_SECRET_KEY" {}
+variable "AWS_ACCESS_KEY" {
+}
+
+variable "AWS_SECRET_KEY" {
+}
+
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
@@ -15,9 +20,12 @@ variable "AMIS" {
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "INSTANCE_USERNAME" {
   default = "ubuntu"
 }
+
diff --git a/demo-2/versions.tf b/demo-2/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-2/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-2b/provider.tf b/demo-2b/provider.tf
index 9f26b63..696b517 100644
--- a/demo-2b/provider.tf
+++ b/demo-2b/provider.tf
@@ -1,6 +1,6 @@
 provider "aws" {
-    access_key = "${var.AWS_ACCESS_KEY}"
-    secret_key = "${var.AWS_SECRET_KEY}"
-    region = "${var.AWS_REGION}"
+  access_key = var.AWS_ACCESS_KEY
+  secret_key = var.AWS_SECRET_KEY
+  region     = var.AWS_REGION
 }
 
diff --git a/demo-2b/vars.tf b/demo-2b/vars.tf
index 4a99dce..df1a83d 100644
--- a/demo-2b/vars.tf
+++ b/demo-2b/vars.tf
@@ -1,10 +1,15 @@
-variable "AWS_ACCESS_KEY" {}
-variable "AWS_SECRET_KEY" {}
+variable "AWS_ACCESS_KEY" {
+}
+
+variable "AWS_SECRET_KEY" {
+}
+
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "WIN_AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-30540427"
     us-west-2 = "ami-9f5efbff"
@@ -15,10 +20,15 @@ variable "WIN_AMIS" {
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "INSTANCE_USERNAME" {
   default = "Terraform"
 }
-variable "INSTANCE_PASSWORD" { }
+
+variable "INSTANCE_PASSWORD" {
+}
+
diff --git a/demo-2b/versions.tf b/demo-2b/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-2b/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-2b/windows-instance.tf b/demo-2b/windows-instance.tf
index 9c39210..a71f743 100644
--- a/demo-2b/windows-instance.tf
+++ b/demo-2b/windows-instance.tf
@@ -1,13 +1,13 @@
 resource "aws_key_pair" "mykey" {
-  key_name = "mykey"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykey"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
 
 resource "aws_instance" "win-example" {
-  ami = "${lookup(var.WIN_AMIS, var.AWS_REGION)}"
+  ami           = var.WIN_AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
-  key_name = "${aws_key_pair.mykey.key_name}"
-  user_data = <<EOF
+  key_name      = aws_key_pair.mykey.key_name
+  user_data     = <<EOF
 <powershell>
 net user ${var.INSTANCE_USERNAME} '${var.INSTANCE_PASSWORD}' /add /y
 net localgroup administrators ${var.INSTANCE_USERNAME} /add
@@ -27,6 +27,7 @@ net start winrm
 </powershell>
 EOF
 
+
   provisioner "file" {
     source = "test.txt"
     destination = "C:/test.txt"
@@ -35,7 +36,8 @@ EOF
     host = coalesce(self.public_ip, self.private_ip)
     type = "winrm"
     timeout = "10m"
-    user = "${var.INSTANCE_USERNAME}"
-    password = "${var.INSTANCE_PASSWORD}"
+    user = var.INSTANCE_USERNAME
+    password = var.INSTANCE_PASSWORD
   }
 }
+
diff --git a/demo-3/instance.tf b/demo-3/instance.tf
index 2623cd0..6511ddf 100644
--- a/demo-3/instance.tf
+++ b/demo-3/instance.tf
@@ -1,10 +1,12 @@
 resource "aws_instance" "example" {
-  ami = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
   provisioner "local-exec" {
-     command = "echo ${aws_instance.example.private_ip} >> private_ips.txt"
+    command = "echo ${aws_instance.example.private_ip} >> private_ips.txt"
   }
 }
+
 output "ip" {
-    value = "${aws_instance.example.public_ip}"
+  value = aws_instance.example.public_ip
 }
+
diff --git a/demo-3/provider.tf b/demo-3/provider.tf
index 9f26b63..696b517 100644
--- a/demo-3/provider.tf
+++ b/demo-3/provider.tf
@@ -1,6 +1,6 @@
 provider "aws" {
-    access_key = "${var.AWS_ACCESS_KEY}"
-    secret_key = "${var.AWS_SECRET_KEY}"
-    region = "${var.AWS_REGION}"
+  access_key = var.AWS_ACCESS_KEY
+  secret_key = var.AWS_SECRET_KEY
+  region     = var.AWS_REGION
 }
 
diff --git a/demo-3/vars.tf b/demo-3/vars.tf
index 2138359..b3c441c 100644
--- a/demo-3/vars.tf
+++ b/demo-3/vars.tf
@@ -1,13 +1,19 @@
-variable "AWS_ACCESS_KEY" {}
-variable "AWS_SECRET_KEY" {}
+variable "AWS_ACCESS_KEY" {
+}
+
+variable "AWS_SECRET_KEY" {
+}
+
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-3/versions.tf b/demo-3/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-3/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-4/instance.tf b/demo-4/instance.tf
index 2623cd0..6511ddf 100644
--- a/demo-4/instance.tf
+++ b/demo-4/instance.tf
@@ -1,10 +1,12 @@
 resource "aws_instance" "example" {
-  ami = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
   provisioner "local-exec" {
-     command = "echo ${aws_instance.example.private_ip} >> private_ips.txt"
+    command = "echo ${aws_instance.example.private_ip} >> private_ips.txt"
   }
 }
+
 output "ip" {
-    value = "${aws_instance.example.public_ip}"
+  value = aws_instance.example.public_ip
 }
+
diff --git a/demo-4/provider.tf b/demo-4/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-4/provider.tf
+++ b/demo-4/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-4/vars.tf b/demo-4/vars.tf
index 504ec30..4d189e0 100644
--- a/demo-4/vars.tf
+++ b/demo-4/vars.tf
@@ -1,11 +1,13 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-4/versions.tf b/demo-4/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-4/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-5/provider.tf b/demo-5/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-5/provider.tf
+++ b/demo-5/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-5/securitygroup.tf b/demo-5/securitygroup.tf
index 2be2f8f..4de36a9 100644
--- a/demo-5/securitygroup.tf
+++ b/demo-5/securitygroup.tf
@@ -1,20 +1,20 @@
 data "aws_ip_ranges" "european_ec2" {
-  regions = [ "eu-west-1", "eu-central-1" ]
-  services = [ "ec2" ]
+  regions  = ["eu-west-1", "eu-central-1"]
+  services = ["ec2"]
 }
 
 resource "aws_security_group" "from_europe" {
- name = "from_europe"
+  name = "from_europe"
 
   ingress {
-    from_port = "443"
-    to_port = "443"
-    protocol = "tcp"
-    cidr_blocks = [ "${data.aws_ip_ranges.european_ec2.cidr_blocks}" ]
+    from_port   = "443"
+    to_port     = "443"
+    protocol    = "tcp"
+    cidr_blocks = data.aws_ip_ranges.european_ec2.cidr_blocks
   }
-  tags {
-    CreateDate = "${data.aws_ip_ranges.european_ec2.create_date}"
-    SyncToken = "${data.aws_ip_ranges.european_ec2.sync_token}"
+  tags = {
+    CreateDate = data.aws_ip_ranges.european_ec2.create_date
+    SyncToken  = data.aws_ip_ranges.european_ec2.sync_token
   }
-
 }
+
diff --git a/demo-5/vars.tf b/demo-5/vars.tf
index 504ec30..4d189e0 100644
--- a/demo-5/vars.tf
+++ b/demo-5/vars.tf
@@ -1,11 +1,13 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-5/versions.tf b/demo-5/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-5/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-6/default_vpc.tf b/demo-6/default_vpc.tf
index 5a6030a..3ab8369 100644
--- a/demo-6/default_vpc.tf
+++ b/demo-6/default_vpc.tf
@@ -4,30 +4,33 @@
 
 # default VPC
 resource "aws_default_vpc" "default" {
-    tags {
-        Name = "Default VPC"
-    }
+  tags = {
+    Name = "Default VPC"
+  }
 }
 
 # default subnets
 resource "aws_default_subnet" "default_az1" {
   availability_zone = "${var.AWS_REGION}a"
 
-    tags {
-        Name = "Default subnet for ${var.AWS_REGION}a"
-    }
+  tags = {
+    Name = "Default subnet for ${var.AWS_REGION}a"
+  }
 }
+
 resource "aws_default_subnet" "default_az2" {
   availability_zone = "${var.AWS_REGION}b"
 
-    tags {
-        Name = "Default subnet for ${var.AWS_REGION}b"
-    }
+  tags = {
+    Name = "Default subnet for ${var.AWS_REGION}b"
+  }
 }
+
 resource "aws_default_subnet" "default_az3" {
   availability_zone = "${var.AWS_REGION}c"
 
-    tags {
-        Name = "Default subnet for ${var.AWS_REGION}c"
-    }
+  tags = {
+    Name = "Default subnet for ${var.AWS_REGION}c"
+  }
 }
+
diff --git a/demo-6/key.tf b/demo-6/key.tf
index 9962e34..de08692 100644
--- a/demo-6/key.tf
+++ b/demo-6/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykey" {
-  key_name = "mykey"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykey"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/demo-6/modules.tf b/demo-6/modules.tf
index 57f878b..6b814c8 100644
--- a/demo-6/modules.tf
+++ b/demo-6/modules.tf
@@ -1,15 +1,17 @@
 module "consul" {
-  source = "github.com/wardviaene/terraform-consul-module.git"
-  key_name = "${aws_key_pair.mykey.key_name}"
-  key_path = "${var.PATH_TO_PRIVATE_KEY}"
-  region = "${var.AWS_REGION}"
-  vpc_id = "${aws_default_vpc.default.id}"
-  subnets {
-    "0" = "${aws_default_subnet.default_az1.id}"
-    "1" = "${aws_default_subnet.default_az2.id}"
-    "2" = "${aws_default_subnet.default_az3.id}"
+  source   = "github.com/wardviaene/terraform-consul-module.git?ref=terraform-0.12"
+  key_name = aws_key_pair.mykey.key_name
+  key_path = var.PATH_TO_PRIVATE_KEY
+  region   = var.AWS_REGION
+  vpc_id   = aws_default_vpc.default.id
+  subnets = {
+    "0" = aws_default_subnet.default_az1.id
+    "1" = aws_default_subnet.default_az2.id
+    "2" = aws_default_subnet.default_az3.id
   }
 }
+
 output "consul-output" {
-  value = "${module.consul.server_address}"
+  value = module.consul.server_address
 }
+
diff --git a/demo-6/provider.tf b/demo-6/provider.tf
index ded6d8c..375d9cd 100644
--- a/demo-6/provider.tf
+++ b/demo-6/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region  = var.AWS_REGION
 }
+
diff --git a/demo-6/vars.tf b/demo-6/vars.tf
index ce2e56b..3878f40 100644
--- a/demo-6/vars.tf
+++ b/demo-6/vars.tf
@@ -1,9 +1,12 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
diff --git a/demo-6/versions.tf b/demo-6/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-6/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-7/nat.tf b/demo-7/nat.tf
index 69f1141..f32efc2 100644
--- a/demo-7/nat.tf
+++ b/demo-7/nat.tf
@@ -1,35 +1,40 @@
 # nat gw
 resource "aws_eip" "nat" {
-  vpc      = true
+  vpc = true
 }
+
 resource "aws_nat_gateway" "nat-gw" {
-  allocation_id = "${aws_eip.nat.id}"
-  subnet_id = "${aws_subnet.main-public-1.id}"
-  depends_on = ["aws_internet_gateway.main-gw"]
+  allocation_id = aws_eip.nat.id
+  subnet_id     = aws_subnet.main-public-1.id
+  depends_on    = [aws_internet_gateway.main-gw]
 }
 
 # VPC setup for NAT
 resource "aws_route_table" "main-private" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        nat_gateway_id = "${aws_nat_gateway.nat-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block     = "0.0.0.0/0"
+    nat_gateway_id = aws_nat_gateway.nat-gw.id
+  }
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 # route associations private
 resource "aws_route_table_association" "main-private-1-a" {
-    subnet_id = "${aws_subnet.main-private-1.id}"
-    route_table_id = "${aws_route_table.main-private.id}"
+  subnet_id      = aws_subnet.main-private-1.id
+  route_table_id = aws_route_table.main-private.id
 }
+
 resource "aws_route_table_association" "main-private-2-a" {
-    subnet_id = "${aws_subnet.main-private-2.id}"
-    route_table_id = "${aws_route_table.main-private.id}"
+  subnet_id      = aws_subnet.main-private-2.id
+  route_table_id = aws_route_table.main-private.id
 }
+
 resource "aws_route_table_association" "main-private-3-a" {
-    subnet_id = "${aws_subnet.main-private-3.id}"
-    route_table_id = "${aws_route_table.main-private.id}"
+  subnet_id      = aws_subnet.main-private-3.id
+  route_table_id = aws_route_table.main-private.id
 }
+
diff --git a/demo-7/provider.tf b/demo-7/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-7/provider.tf
+++ b/demo-7/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-7/vars.tf b/demo-7/vars.tf
index ce2e56b..3878f40 100644
--- a/demo-7/vars.tf
+++ b/demo-7/vars.tf
@@ -1,9 +1,12 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
diff --git a/demo-7/versions.tf b/demo-7/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-7/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-7/vpc.tf b/demo-7/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-7/vpc.tf
+++ b/demo-7/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/demo-8/instance.tf b/demo-8/instance.tf
index f4daa01..7f00edc 100644
--- a/demo-8/instance.tf
+++ b/demo-8/instance.tf
@@ -1,13 +1,14 @@
 resource "aws_instance" "example" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.allow-ssh.id}"]
+  vpc_security_group_ids = [aws_security_group.allow-ssh.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 }
+
diff --git a/demo-8/key.tf b/demo-8/key.tf
index 0d3c220..58b093f 100644
--- a/demo-8/key.tf
+++ b/demo-8/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/demo-8/provider.tf b/demo-8/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-8/provider.tf
+++ b/demo-8/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-8/securitygroup.tf b/demo-8/securitygroup.tf
index 05c0e12..1ec204b 100644
--- a/demo-8/securitygroup.tf
+++ b/demo-8/securitygroup.tf
@@ -1,21 +1,22 @@
 resource "aws_security_group" "allow-ssh" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-ssh"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "allow-ssh"
   }
 }
+
diff --git a/demo-8/vars.tf b/demo-8/vars.tf
index d880ef6..2712edf 100644
--- a/demo-8/vars.tf
+++ b/demo-8/vars.tf
@@ -1,17 +1,21 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-8/versions.tf b/demo-8/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-8/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-8/vpc.tf b/demo-8/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-8/vpc.tf
+++ b/demo-8/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/demo-9/instance.tf b/demo-9/instance.tf
index e615b01..88c1183 100644
--- a/demo-9/instance.tf
+++ b/demo-9/instance.tf
@@ -1,29 +1,29 @@
 resource "aws_instance" "example" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.allow-ssh.id}"]
+  vpc_security_group_ids = [aws_security_group.allow-ssh.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 }
 
 resource "aws_ebs_volume" "ebs-volume-1" {
-    availability_zone = "eu-west-1a"
-    size = 20
-    type = "gp2" 
-    tags {
-        Name = "extra volume data"
-    }
+  availability_zone = "eu-west-1a"
+  size              = 20
+  type              = "gp2"
+  tags = {
+    Name = "extra volume data"
+  }
 }
 
 resource "aws_volume_attachment" "ebs-volume-1-attachment" {
   device_name = "/dev/xvdh"
-  volume_id = "${aws_ebs_volume.ebs-volume-1.id}"
-  instance_id = "${aws_instance.example.id}"
+  volume_id   = aws_ebs_volume.ebs-volume-1.id
+  instance_id = aws_instance.example.id
 }
 
diff --git a/demo-9/key.tf b/demo-9/key.tf
index 0d3c220..58b093f 100644
--- a/demo-9/key.tf
+++ b/demo-9/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/demo-9/provider.tf b/demo-9/provider.tf
index ded6d8c..7925c73 100644
--- a/demo-9/provider.tf
+++ b/demo-9/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/demo-9/securitygroup.tf b/demo-9/securitygroup.tf
index 05c0e12..1ec204b 100644
--- a/demo-9/securitygroup.tf
+++ b/demo-9/securitygroup.tf
@@ -1,21 +1,22 @@
 resource "aws_security_group" "allow-ssh" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-ssh"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "allow-ssh"
   }
 }
+
diff --git a/demo-9/vars.tf b/demo-9/vars.tf
index d880ef6..2712edf 100644
--- a/demo-9/vars.tf
+++ b/demo-9/vars.tf
@@ -1,17 +1,21 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
diff --git a/demo-9/versions.tf b/demo-9/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/demo-9/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/demo-9/vpc.tf b/demo-9/vpc.tf
index 1325feb..4e9d809 100644
--- a/demo-9/vpc.tf
+++ b/demo-9/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/docker-demo-1/ecr.tf b/docker-demo-1/ecr.tf
index c136228..addea5d 100644
--- a/docker-demo-1/ecr.tf
+++ b/docker-demo-1/ecr.tf
@@ -1,3 +1,4 @@
 resource "aws_ecr_repository" "myapp" {
   name = "myapp"
 }
+
diff --git a/docker-demo-1/output.tf b/docker-demo-1/output.tf
index 0dd1091..b7702af 100644
--- a/docker-demo-1/output.tf
+++ b/docker-demo-1/output.tf
@@ -1,3 +1,4 @@
 output "myapp-repository-URL" {
-  value = "${aws_ecr_repository.myapp.repository_url}"
+  value = aws_ecr_repository.myapp.repository_url
 }
+
diff --git a/docker-demo-1/provider.tf b/docker-demo-1/provider.tf
index 5a52b53..7925c73 100644
--- a/docker-demo-1/provider.tf
+++ b/docker-demo-1/provider.tf
@@ -1,4 +1,4 @@
 provider "aws" {
-    region = "${var.AWS_REGION}"
+  region = var.AWS_REGION
 }
 
diff --git a/docker-demo-1/vars.tf b/docker-demo-1/vars.tf
index 7c29d8c..ac7990c 100644
--- a/docker-demo-1/vars.tf
+++ b/docker-demo-1/vars.tf
@@ -1,3 +1,4 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
diff --git a/docker-demo-1/versions.tf b/docker-demo-1/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/docker-demo-1/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/docker-demo-2/ecr.tf b/docker-demo-2/ecr.tf
index c136228..addea5d 100644
--- a/docker-demo-2/ecr.tf
+++ b/docker-demo-2/ecr.tf
@@ -1,3 +1,4 @@
 resource "aws_ecr_repository" "myapp" {
   name = "myapp"
 }
+
diff --git a/docker-demo-2/ecs.tf b/docker-demo-2/ecs.tf
index 4dc7f7e..905bf69 100644
--- a/docker-demo-2/ecs.tf
+++ b/docker-demo-2/ecs.tf
@@ -1,28 +1,31 @@
 # cluster
 resource "aws_ecs_cluster" "example-cluster" {
-    name = "example-cluster"
+  name = "example-cluster"
 }
+
 resource "aws_launch_configuration" "ecs-example-launchconfig" {
   name_prefix          = "ecs-launchconfig"
-  image_id             = "${lookup(var.ECS_AMIS, var.AWS_REGION)}"
-  instance_type        = "${var.ECS_INSTANCE_TYPE}"
-  key_name             = "${aws_key_pair.mykeypair.key_name}"
-  iam_instance_profile = "${aws_iam_instance_profile.ecs-ec2-role.id}"
-  security_groups      = ["${aws_security_group.ecs-securitygroup.id}"]
+  image_id             = var.ECS_AMIS[var.AWS_REGION]
+  instance_type        = var.ECS_INSTANCE_TYPE
+  key_name             = aws_key_pair.mykeypair.key_name
+  iam_instance_profile = aws_iam_instance_profile.ecs-ec2-role.id
+  security_groups      = [aws_security_group.ecs-securitygroup.id]
   user_data            = "#!/bin/bash\necho 'ECS_CLUSTER=example-cluster' > /etc/ecs/ecs.config\nstart ecs"
-  lifecycle              { create_before_destroy = true }
-}
-resource "aws_autoscaling_group" "ecs-example-autoscaling" {
-  name                 = "ecs-example-autoscaling"
-  vpc_zone_identifier  = ["${aws_subnet.main-public-1.id}", "${aws_subnet.main-public-2.id}"]
-  launch_configuration = "${aws_launch_configuration.ecs-example-launchconfig.name}"
-  min_size             = 1
-  max_size             = 1
-  tag {
-      key = "Name"
-      value = "ecs-ec2-container"
-      propagate_at_launch = true
+  lifecycle {
+    create_before_destroy = true
   }
 }
 
+resource "aws_autoscaling_group" "ecs-example-autoscaling" {
+  name                 = "ecs-example-autoscaling"
+  vpc_zone_identifier  = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
+  launch_configuration = aws_launch_configuration.ecs-example-launchconfig.name
+  min_size             = 1
+  max_size             = 1
+  tag {
+    key                 = "Name"
+    value               = "ecs-ec2-container"
+    propagate_at_launch = true
+  }
+}
 
diff --git a/docker-demo-2/iam.tf b/docker-demo-2/iam.tf
index 2d9b1ff..64a2b59 100644
--- a/docker-demo-2/iam.tf
+++ b/docker-demo-2/iam.tf
@@ -1,7 +1,7 @@
 # ecs ec2 role
 resource "aws_iam_role" "ecs-ec2-role" {
-    name = "ecs-ec2-role"
-    assume_role_policy = <<EOF
+  name               = "ecs-ec2-role"
+  assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -16,15 +16,17 @@ resource "aws_iam_role" "ecs-ec2-role" {
   ]
 }
 EOF
+
 }
+
 resource "aws_iam_instance_profile" "ecs-ec2-role" {
-    name = "ecs-ec2-role"
-    role = "${aws_iam_role.ecs-ec2-role.name}"
+  name = "ecs-ec2-role"
+  role = aws_iam_role.ecs-ec2-role.name
 }
 
 resource "aws_iam_role" "ecs-consul-server-role" {
-    name = "ecs-consul-server-role"
-    assume_role_policy = <<EOF
+  name = "ecs-consul-server-role"
+  assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -39,12 +41,13 @@ resource "aws_iam_role" "ecs-consul-server-role" {
   ]
 }
 EOF
+
 }
 
 resource "aws_iam_role_policy" "ecs-ec2-role-policy" {
-    name = "ecs-ec2-role-policy"
-    role = "${aws_iam_role.ecs-ec2-role.id}"
-    policy = <<EOF
+name   = "ecs-ec2-role-policy"
+role   = aws_iam_role.ecs-ec2-role.id
+policy = <<EOF
 {
     "Version": "2012-10-17",
     "Statement": [
@@ -83,12 +86,13 @@ resource "aws_iam_role_policy" "ecs-ec2-role-policy" {
     ]
 }
 EOF
+
 }
 
 # ecs service role
 resource "aws_iam_role" "ecs-service-role" {
-    name = "ecs-service-role"
-    assume_role_policy = <<EOF
+name = "ecs-service-role"
+assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -103,11 +107,12 @@ resource "aws_iam_role" "ecs-service-role" {
   ]
 }
 EOF
+
 }
 
 resource "aws_iam_policy_attachment" "ecs-service-attach1" {
-    name = "ecs-service-attach1"
-    roles = ["${aws_iam_role.ecs-service-role.name}"]
-    policy_arn = "arn:aws:iam::aws:policy/service-role/AmazonEC2ContainerServiceRole"
+  name       = "ecs-service-attach1"
+  roles      = [aws_iam_role.ecs-service-role.name]
+  policy_arn = "arn:aws:iam::aws:policy/service-role/AmazonEC2ContainerServiceRole"
 }
 
diff --git a/docker-demo-2/key.tf b/docker-demo-2/key.tf
index 278a5a9..b41e059 100644
--- a/docker-demo-2/key.tf
+++ b/docker-demo-2/key.tf
@@ -1,7 +1,8 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
   lifecycle {
-    ignore_changes = ["public_key"]
+    ignore_changes = [public_key]
   }
 }
+
diff --git a/docker-demo-2/myapp.tf b/docker-demo-2/myapp.tf
index e994559..5851179 100644
--- a/docker-demo-2/myapp.tf
+++ b/docker-demo-2/myapp.tf
@@ -1,61 +1,63 @@
 # app
 
 data "template_file" "myapp-task-definition-template" {
-  template               = "${file("templates/app.json.tpl")}"
-  vars {
-    REPOSITORY_URL = "${replace("${aws_ecr_repository.myapp.repository_url}", "https://", "")}"
+  template = file("templates/app.json.tpl")
+  vars = {
+    REPOSITORY_URL = replace(aws_ecr_repository.myapp.repository_url, "https://", "")
   }
 }
 
 resource "aws_ecs_task_definition" "myapp-task-definition" {
   family                = "myapp"
-  container_definitions = "${data.template_file.myapp-task-definition-template.rendered}"
+  container_definitions = data.template_file.myapp-task-definition-template.rendered
 }
 
 resource "aws_elb" "myapp-elb" {
   name = "myapp-elb"
 
   listener {
-    instance_port = 3000
+    instance_port     = 3000
     instance_protocol = "http"
-    lb_port = 80
-    lb_protocol = "http"
+    lb_port           = 80
+    lb_protocol       = "http"
   }
 
   health_check {
-    healthy_threshold = 3
+    healthy_threshold   = 3
     unhealthy_threshold = 3
-    timeout = 30
-    target = "HTTP:3000/"
-    interval = 60
+    timeout             = 30
+    target              = "HTTP:3000/"
+    interval            = 60
   }
 
-  cross_zone_load_balancing = true
-  idle_timeout = 400
-  connection_draining = true
+  cross_zone_load_balancing   = true
+  idle_timeout                = 400
+  connection_draining         = true
   connection_draining_timeout = 400
 
-  subnets = ["${aws_subnet.main-public-1.id}","${aws_subnet.main-public-2.id}"]
-  security_groups = ["${aws_security_group.myapp-elb-securitygroup.id}"]
+  subnets         = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
+  security_groups = [aws_security_group.myapp-elb-securitygroup.id]
 
-  tags {
+  tags = {
     Name = "myapp-elb"
   }
 }
 
 resource "aws_ecs_service" "myapp-service" {
-  name = "myapp"
-  cluster = "${aws_ecs_cluster.example-cluster.id}"
-  task_definition = "${aws_ecs_task_definition.myapp-task-definition.arn}"
-  desired_count = 1
-  iam_role = "${aws_iam_role.ecs-service-role.arn}"
-  depends_on = ["aws_iam_policy_attachment.ecs-service-attach1"]
+  name            = "myapp"
+  cluster         = aws_ecs_cluster.example-cluster.id
+  task_definition = aws_ecs_task_definition.myapp-task-definition.arn
+  desired_count   = 1
+  iam_role        = aws_iam_role.ecs-service-role.arn
+  depends_on      = [aws_iam_policy_attachment.ecs-service-attach1]
 
   load_balancer {
-    elb_name = "${aws_elb.myapp-elb.name}"
+    elb_name       = aws_elb.myapp-elb.name
     container_name = "myapp"
     container_port = 3000
   }
-  lifecycle { ignore_changes = ["task_definition"] }
+  lifecycle {
+    ignore_changes = [task_definition]
+  }
 }
 
diff --git a/docker-demo-2/output.tf b/docker-demo-2/output.tf
index 87c3237..7c5be67 100644
--- a/docker-demo-2/output.tf
+++ b/docker-demo-2/output.tf
@@ -1,3 +1,4 @@
 output "elb" {
-  value = "${aws_elb.myapp-elb.dns_name}"
+  value = aws_elb.myapp-elb.dns_name
 }
+
diff --git a/docker-demo-2/provider.tf b/docker-demo-2/provider.tf
index ded6d8c..7925c73 100644
--- a/docker-demo-2/provider.tf
+++ b/docker-demo-2/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/docker-demo-2/securitygroup.tf b/docker-demo-2/securitygroup.tf
index 51d18da..e2b7550 100644
--- a/docker-demo-2/securitygroup.tf
+++ b/docker-demo-2/securitygroup.tf
@@ -1,48 +1,50 @@
 resource "aws_security_group" "ecs-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "ecs"
+  vpc_id      = aws_vpc.main.id
+  name        = "ecs"
   description = "security group for ecs"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 3000
-      to_port = 3000
-      protocol = "tcp"
-      security_groups = ["${aws_security_group.myapp-elb-securitygroup.id}"]
-  } 
+    from_port       = 3000
+    to_port         = 3000
+    protocol        = "tcp"
+    security_groups = [aws_security_group.myapp-elb-securitygroup.id]
+  }
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-  tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "ecs"
   }
 }
+
 resource "aws_security_group" "myapp-elb-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "myapp-elb"
+  vpc_id      = aws_vpc.main.id
+  name        = "myapp-elb"
   description = "security group for ecs"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 80
-      to_port = 80
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-  tags {
+    from_port   = 80
+    to_port     = 80
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "myapp-elb"
   }
 }
+
diff --git a/docker-demo-2/vars.tf b/docker-demo-2/vars.tf
index a52c3d4..c7f9c8a 100644
--- a/docker-demo-2/vars.tf
+++ b/docker-demo-2/vars.tf
@@ -1,21 +1,26 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "ECS_INSTANCE_TYPE" {
   default = "t2.micro"
 }
+
 variable "ECS_AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-1924770e"
     us-west-2 = "ami-56ed4936"
     eu-west-1 = "ami-c8337dbb"
   }
 }
+
 # Full List: http://docs.aws.amazon.com/AmazonECS/latest/developerguide/ecs-optimized_AMI.html
diff --git a/docker-demo-2/versions.tf b/docker-demo-2/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/docker-demo-2/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/docker-demo-2/vpc.tf b/docker-demo-2/vpc.tf
index 1325feb..4e9d809 100644
--- a/docker-demo-2/vpc.tf
+++ b/docker-demo-2/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/docker-demo-3/cloudinit.tf b/docker-demo-3/cloudinit.tf
index 82162b5..8349a64 100644
--- a/docker-demo-3/cloudinit.tf
+++ b/docker-demo-3/cloudinit.tf
@@ -1,18 +1,18 @@
 data "template_file" "jenkins-init" {
-  template = "${file("scripts/jenkins-init.sh")}"
-  vars {
-    DEVICE = "${var.INSTANCE_DEVICE_NAME}"
-    JENKINS_VERSION = "${var.JENKINS_VERSION}"
+  template = file("scripts/jenkins-init.sh")
+  vars = {
+    DEVICE          = var.INSTANCE_DEVICE_NAME
+    JENKINS_VERSION = var.JENKINS_VERSION
   }
 }
-data "template_cloudinit_config" "cloudinit-jenkins" {
 
-  gzip = false
+data "template_cloudinit_config" "cloudinit-jenkins" {
+  gzip          = false
   base64_encode = false
 
   part {
     content_type = "text/x-shellscript"
-    content      = "${data.template_file.jenkins-init.rendered}"
+    content      = data.template_file.jenkins-init.rendered
   }
-
 }
+
diff --git a/docker-demo-3/ecr.tf b/docker-demo-3/ecr.tf
index c136228..addea5d 100644
--- a/docker-demo-3/ecr.tf
+++ b/docker-demo-3/ecr.tf
@@ -1,3 +1,4 @@
 resource "aws_ecr_repository" "myapp" {
   name = "myapp"
 }
+
diff --git a/docker-demo-3/ecs.tf b/docker-demo-3/ecs.tf
index 4dc7f7e..905bf69 100644
--- a/docker-demo-3/ecs.tf
+++ b/docker-demo-3/ecs.tf
@@ -1,28 +1,31 @@
 # cluster
 resource "aws_ecs_cluster" "example-cluster" {
-    name = "example-cluster"
+  name = "example-cluster"
 }
+
 resource "aws_launch_configuration" "ecs-example-launchconfig" {
   name_prefix          = "ecs-launchconfig"
-  image_id             = "${lookup(var.ECS_AMIS, var.AWS_REGION)}"
-  instance_type        = "${var.ECS_INSTANCE_TYPE}"
-  key_name             = "${aws_key_pair.mykeypair.key_name}"
-  iam_instance_profile = "${aws_iam_instance_profile.ecs-ec2-role.id}"
-  security_groups      = ["${aws_security_group.ecs-securitygroup.id}"]
+  image_id             = var.ECS_AMIS[var.AWS_REGION]
+  instance_type        = var.ECS_INSTANCE_TYPE
+  key_name             = aws_key_pair.mykeypair.key_name
+  iam_instance_profile = aws_iam_instance_profile.ecs-ec2-role.id
+  security_groups      = [aws_security_group.ecs-securitygroup.id]
   user_data            = "#!/bin/bash\necho 'ECS_CLUSTER=example-cluster' > /etc/ecs/ecs.config\nstart ecs"
-  lifecycle              { create_before_destroy = true }
-}
-resource "aws_autoscaling_group" "ecs-example-autoscaling" {
-  name                 = "ecs-example-autoscaling"
-  vpc_zone_identifier  = ["${aws_subnet.main-public-1.id}", "${aws_subnet.main-public-2.id}"]
-  launch_configuration = "${aws_launch_configuration.ecs-example-launchconfig.name}"
-  min_size             = 1
-  max_size             = 1
-  tag {
-      key = "Name"
-      value = "ecs-ec2-container"
-      propagate_at_launch = true
+  lifecycle {
+    create_before_destroy = true
   }
 }
 
+resource "aws_autoscaling_group" "ecs-example-autoscaling" {
+  name                 = "ecs-example-autoscaling"
+  vpc_zone_identifier  = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
+  launch_configuration = aws_launch_configuration.ecs-example-launchconfig.name
+  min_size             = 1
+  max_size             = 1
+  tag {
+    key                 = "Name"
+    value               = "ecs-ec2-container"
+    propagate_at_launch = true
+  }
+}
 
diff --git a/docker-demo-3/iam.tf b/docker-demo-3/iam.tf
index 2d9b1ff..64a2b59 100644
--- a/docker-demo-3/iam.tf
+++ b/docker-demo-3/iam.tf
@@ -1,7 +1,7 @@
 # ecs ec2 role
 resource "aws_iam_role" "ecs-ec2-role" {
-    name = "ecs-ec2-role"
-    assume_role_policy = <<EOF
+  name               = "ecs-ec2-role"
+  assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -16,15 +16,17 @@ resource "aws_iam_role" "ecs-ec2-role" {
   ]
 }
 EOF
+
 }
+
 resource "aws_iam_instance_profile" "ecs-ec2-role" {
-    name = "ecs-ec2-role"
-    role = "${aws_iam_role.ecs-ec2-role.name}"
+  name = "ecs-ec2-role"
+  role = aws_iam_role.ecs-ec2-role.name
 }
 
 resource "aws_iam_role" "ecs-consul-server-role" {
-    name = "ecs-consul-server-role"
-    assume_role_policy = <<EOF
+  name = "ecs-consul-server-role"
+  assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -39,12 +41,13 @@ resource "aws_iam_role" "ecs-consul-server-role" {
   ]
 }
 EOF
+
 }
 
 resource "aws_iam_role_policy" "ecs-ec2-role-policy" {
-    name = "ecs-ec2-role-policy"
-    role = "${aws_iam_role.ecs-ec2-role.id}"
-    policy = <<EOF
+name   = "ecs-ec2-role-policy"
+role   = aws_iam_role.ecs-ec2-role.id
+policy = <<EOF
 {
     "Version": "2012-10-17",
     "Statement": [
@@ -83,12 +86,13 @@ resource "aws_iam_role_policy" "ecs-ec2-role-policy" {
     ]
 }
 EOF
+
 }
 
 # ecs service role
 resource "aws_iam_role" "ecs-service-role" {
-    name = "ecs-service-role"
-    assume_role_policy = <<EOF
+name = "ecs-service-role"
+assume_role_policy = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
@@ -103,11 +107,12 @@ resource "aws_iam_role" "ecs-service-role" {
   ]
 }
 EOF
+
 }
 
 resource "aws_iam_policy_attachment" "ecs-service-attach1" {
-    name = "ecs-service-attach1"
-    roles = ["${aws_iam_role.ecs-service-role.name}"]
-    policy_arn = "arn:aws:iam::aws:policy/service-role/AmazonEC2ContainerServiceRole"
+  name       = "ecs-service-attach1"
+  roles      = [aws_iam_role.ecs-service-role.name]
+  policy_arn = "arn:aws:iam::aws:policy/service-role/AmazonEC2ContainerServiceRole"
 }
 
diff --git a/docker-demo-3/jenkins.tf b/docker-demo-3/jenkins.tf
index f8d7a2e..4f22287 100644
--- a/docker-demo-3/jenkins.tf
+++ b/docker-demo-3/jenkins.tf
@@ -1,33 +1,32 @@
 resource "aws_instance" "jenkins-instance" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.small"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.jenkins-securitygroup.id}"]
+  vpc_security_group_ids = [aws_security_group.jenkins-securitygroup.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 
   # user data
-  user_data = "${data.template_cloudinit_config.cloudinit-jenkins.rendered}"
-
+  user_data = data.template_cloudinit_config.cloudinit-jenkins.rendered
 }
 
 resource "aws_ebs_volume" "jenkins-data" {
-    availability_zone = "eu-west-1a"
-    size = 20
-    type = "gp2" 
-    tags {
-        Name = "jenkins-data"
-    }
+  availability_zone = "eu-west-1a"
+  size              = 20
+  type              = "gp2"
+  tags = {
+    Name = "jenkins-data"
+  }
 }
 
 resource "aws_volume_attachment" "jenkins-data-attachment" {
-  device_name = "${var.INSTANCE_DEVICE_NAME}"
-  volume_id = "${aws_ebs_volume.jenkins-data.id}"
-  instance_id = "${aws_instance.jenkins-instance.id}"
+  device_name = var.INSTANCE_DEVICE_NAME
+  volume_id   = aws_ebs_volume.jenkins-data.id
+  instance_id = aws_instance.jenkins-instance.id
 }
 
diff --git a/docker-demo-3/key.tf b/docker-demo-3/key.tf
index 278a5a9..b41e059 100644
--- a/docker-demo-3/key.tf
+++ b/docker-demo-3/key.tf
@@ -1,7 +1,8 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
   lifecycle {
-    ignore_changes = ["public_key"]
+    ignore_changes = [public_key]
   }
 }
+
diff --git a/docker-demo-3/myapp-vars.tf b/docker-demo-3/myapp-vars.tf
index 27f14ff..591f1a9 100644
--- a/docker-demo-3/myapp-vars.tf
+++ b/docker-demo-3/myapp-vars.tf
@@ -1,2 +1,8 @@
-variable "MYAPP_SERVICE_ENABLE" { default = "0" }
-variable "MYAPP_VERSION" { default = "0" }
+variable "MYAPP_SERVICE_ENABLE" {
+  default = "0"
+}
+
+variable "MYAPP_VERSION" {
+  default = "0"
+}
+
diff --git a/docker-demo-3/myapp.tf b/docker-demo-3/myapp.tf
index e0c3d36..d30b744 100644
--- a/docker-demo-3/myapp.tf
+++ b/docker-demo-3/myapp.tf
@@ -1,33 +1,35 @@
 # app
 
 data "template_file" "myapp-task-definition-template" {
-  template               = "${file("templates/app.json.tpl")}"
-  vars {
-    REPOSITORY_URL = "${replace("${aws_ecr_repository.myapp.repository_url}", "https://", "")}"
-    APP_VERSION = "${var.MYAPP_VERSION}"
+  template = file("templates/app.json.tpl")
+  vars = {
+    REPOSITORY_URL = replace(aws_ecr_repository.myapp.repository_url, "https://", "")
+    APP_VERSION    = var.MYAPP_VERSION
   }
 }
 
 resource "aws_ecs_task_definition" "myapp-task-definition" {
   family                = "myapp"
-  container_definitions = "${data.template_file.myapp-task-definition-template.rendered}"
+  container_definitions = data.template_file.myapp-task-definition-template.rendered
 }
 
 resource "aws_ecs_service" "myapp-service" {
-  count = "${var.MYAPP_SERVICE_ENABLE}"
-  name = "myapp"
-  cluster = "${aws_ecs_cluster.example-cluster.id}"
-  task_definition = "${aws_ecs_task_definition.myapp-task-definition.arn}"
-  desired_count = 1
-  iam_role = "${aws_iam_role.ecs-service-role.arn}"
-  depends_on = ["aws_iam_policy_attachment.ecs-service-attach1"]
+  count           = var.MYAPP_SERVICE_ENABLE
+  name            = "myapp"
+  cluster         = aws_ecs_cluster.example-cluster.id
+  task_definition = aws_ecs_task_definition.myapp-task-definition.arn
+  desired_count   = 1
+  iam_role        = aws_iam_role.ecs-service-role.arn
+  depends_on      = [aws_iam_policy_attachment.ecs-service-attach1]
 
   load_balancer {
-    elb_name = "${aws_elb.myapp-elb.name}"
+    elb_name       = aws_elb.myapp-elb.name
     container_name = "myapp"
     container_port = 3000
   }
-  lifecycle { ignore_changes = ["task_definition"] }
+  lifecycle {
+    ignore_changes = [task_definition]
+  }
 }
 
 # load balancer
@@ -35,29 +37,29 @@ resource "aws_elb" "myapp-elb" {
   name = "myapp-elb"
 
   listener {
-    instance_port = 3000
+    instance_port     = 3000
     instance_protocol = "http"
-    lb_port = 80
-    lb_protocol = "http"
+    lb_port           = 80
+    lb_protocol       = "http"
   }
 
   health_check {
-    healthy_threshold = 3
+    healthy_threshold   = 3
     unhealthy_threshold = 3
-    timeout = 30
-    target = "HTTP:3000/"
-    interval = 60
+    timeout             = 30
+    target              = "HTTP:3000/"
+    interval            = 60
   }
 
-  cross_zone_load_balancing = true
-  idle_timeout = 400
-  connection_draining = true
+  cross_zone_load_balancing   = true
+  idle_timeout                = 400
+  connection_draining         = true
   connection_draining_timeout = 400
 
-  subnets = ["${aws_subnet.main-public-1.id}","${aws_subnet.main-public-2.id}"]
-  security_groups = ["${aws_security_group.myapp-elb-securitygroup.id}"]
+  subnets         = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
+  security_groups = [aws_security_group.myapp-elb-securitygroup.id]
 
-  tags {
+  tags = {
     Name = "myapp-elb"
   }
 }
diff --git a/docker-demo-3/output.tf b/docker-demo-3/output.tf
index 5f4ad4c..4f6b5dd 100644
--- a/docker-demo-3/output.tf
+++ b/docker-demo-3/output.tf
@@ -1,9 +1,12 @@
 output "elb" {
-  value = "${aws_elb.myapp-elb.dns_name}"
+  value = aws_elb.myapp-elb.dns_name
 }
+
 output "jenkins" {
-  value = "${aws_instance.jenkins-instance.public_ip}"
+  value = aws_instance.jenkins-instance.public_ip
 }
+
 output "myapp-repository-URL" {
-  value = "${aws_ecr_repository.myapp.repository_url}"
+  value = aws_ecr_repository.myapp.repository_url
 }
+
diff --git a/docker-demo-3/provider.tf b/docker-demo-3/provider.tf
index ded6d8c..7925c73 100644
--- a/docker-demo-3/provider.tf
+++ b/docker-demo-3/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/docker-demo-3/s3.tf b/docker-demo-3/s3.tf
index b9afaaf..9055dde 100644
--- a/docker-demo-3/s3.tf
+++ b/docker-demo-3/s3.tf
@@ -1,8 +1,9 @@
 resource "aws_s3_bucket" "terraform-state" {
-    bucket = "terraform-state-a2b6219"
-    acl = "private"
+  bucket = "terraform-state-a2b6219"
+  acl    = "private"
 
-    tags {
-        Name = "Terraform state"
-    }
+  tags = {
+    Name = "Terraform state"
+  }
 }
+
diff --git a/docker-demo-3/securitygroup.tf b/docker-demo-3/securitygroup.tf
index 60f749b..b5d3744 100644
--- a/docker-demo-3/securitygroup.tf
+++ b/docker-demo-3/securitygroup.tf
@@ -1,76 +1,79 @@
 resource "aws_security_group" "ecs-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "ecs"
+  vpc_id      = aws_vpc.main.id
+  name        = "ecs"
   description = "security group for ecs"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 3000
-      to_port = 3000
-      protocol = "tcp"
-      security_groups = ["${aws_security_group.myapp-elb-securitygroup.id}"]
-  } 
+    from_port       = 3000
+    to_port         = 3000
+    protocol        = "tcp"
+    security_groups = [aws_security_group.myapp-elb-securitygroup.id]
+  }
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-  tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "ecs"
   }
 }
+
 resource "aws_security_group" "myapp-elb-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "myapp-elb"
+  vpc_id      = aws_vpc.main.id
+  name        = "myapp-elb"
   description = "security group for ecs"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 80
-      to_port = 80
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-  tags {
+    from_port   = 80
+    to_port     = 80
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "myapp-elb"
   }
 }
+
 # jenkins
 resource "aws_security_group" "jenkins-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "jenkins-securitygroup"
+  vpc_id      = aws_vpc.main.id
+  name        = "jenkins-securitygroup"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
   ingress {
-      from_port = 8080
-      to_port = 8080
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 8080
+    to_port     = 8080
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "jenkins-securitygroup"
   }
 }
+
diff --git a/docker-demo-3/vars.tf b/docker-demo-3/vars.tf
index b265163..5c3b42f 100644
--- a/docker-demo-3/vars.tf
+++ b/docker-demo-3/vars.tf
@@ -1,36 +1,43 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "ECS_INSTANCE_TYPE" {
   default = "t2.micro"
 }
+
 variable "ECS_AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-1924770e"
     us-west-2 = "ami-56ed4936"
     eu-west-1 = "ami-c8337dbb"
   }
 }
+
 # Full List: http://docs.aws.amazon.com/AmazonECS/latest/developerguide/ecs-optimized_AMI.html
 
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
 variable "INSTANCE_DEVICE_NAME" {
   default = "/dev/xvdh"
 }
+
 variable "JENKINS_VERSION" {
   default = "2.73.2"
 }
diff --git a/docker-demo-3/versions.tf b/docker-demo-3/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/docker-demo-3/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/docker-demo-3/vpc.tf b/docker-demo-3/vpc.tf
index 1325feb..4e9d809 100644
--- a/docker-demo-3/vpc.tf
+++ b/docker-demo-3/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/eks-demo/eks-cluster.tf b/eks-demo/eks-cluster.tf
index 218965d..bb7c44d 100644
--- a/eks-demo/eks-cluster.tf
+++ b/eks-demo/eks-cluster.tf
@@ -1,15 +1,23 @@
 resource "aws_eks_cluster" "demo" {
-  name     = "${var.cluster-name}"
-  role_arn = "${aws_iam_role.demo-cluster.arn}"
+  name     = var.cluster-name
+  role_arn = aws_iam_role.demo-cluster.arn
 
   vpc_config {
-    security_group_ids = ["${aws_security_group.demo-cluster.id}"]
-    subnet_ids         = ["${module.vpc.public_subnets}"]
+    security_group_ids = [aws_security_group.demo-cluster.id]
+    # TF-UPGRADE-TODO: In Terraform v0.10 and earlier, it was sometimes necessary to
+    # force an interpolation expression to be interpreted as a list by wrapping it
+    # in an extra set of list brackets. That form was supported for compatibilty in
+    # v0.11, but is no longer supported in Terraform v0.12.
+    #
+    # If the expression in the following list itself returns a list, remove the
+    # brackets to avoid interpretation as a list of lists. If the expression
+    # returns a single list item then leave it as-is and remove this TODO comment.
+    subnet_ids = module.vpc.public_subnets
   }
 
   depends_on = [
-    "aws_iam_role_policy_attachment.demo-cluster-AmazonEKSClusterPolicy",
-    "aws_iam_role_policy_attachment.demo-cluster-AmazonEKSServicePolicy",
+    aws_iam_role_policy_attachment.demo-cluster-AmazonEKSClusterPolicy,
+    aws_iam_role_policy_attachment.demo-cluster-AmazonEKSServicePolicy,
   ]
 }
 
diff --git a/eks-demo/eks-workers.tf b/eks-demo/eks-workers.tf
index 3339370..2d462a0 100644
--- a/eks-demo/eks-workers.tf
+++ b/eks-demo/eks-workers.tf
@@ -17,18 +17,19 @@ locals {
   demo-node-userdata = <<USERDATA
 #!/bin/bash
 set -o xtrace
-/etc/eks/bootstrap.sh --apiserver-endpoint '${aws_eks_cluster.demo.endpoint}' --b64-cluster-ca '${aws_eks_cluster.demo.certificate_authority.0.data}' '${var.cluster-name}'
+/etc/eks/bootstrap.sh --apiserver-endpoint '${aws_eks_cluster.demo.endpoint}' --b64-cluster-ca '${aws_eks_cluster.demo.certificate_authority[0].data}' '${var.cluster-name}'
 USERDATA
+
 }
 
 resource "aws_launch_configuration" "demo" {
   associate_public_ip_address = true
-  iam_instance_profile        = "${aws_iam_instance_profile.demo-node.name}"
-  image_id                    = "${data.aws_ami.eks-worker.id}"
-  instance_type               = "t2.large"
-  name_prefix                 = "terraform-eks-demo"
-  security_groups             = ["${aws_security_group.demo-node.id}"]
-  user_data_base64            = "${base64encode(local.demo-node-userdata)}"
+  iam_instance_profile = aws_iam_instance_profile.demo-node.name
+  image_id = data.aws_ami.eks-worker.id
+  instance_type = "t2.large"
+  name_prefix = "terraform-eks-demo"
+  security_groups = [aws_security_group.demo-node.id]
+  user_data_base64 = base64encode(local.demo-node-userdata)
 
   lifecycle {
     create_before_destroy = true
@@ -36,22 +37,31 @@ resource "aws_launch_configuration" "demo" {
 }
 
 resource "aws_autoscaling_group" "demo" {
-  desired_capacity     = 2
-  launch_configuration = "${aws_launch_configuration.demo.id}"
-  max_size             = 2
-  min_size             = 1
-  name                 = "terraform-eks-demo"
-  vpc_zone_identifier  = ["${module.vpc.public_subnets}"]
+  desired_capacity = 2
+  launch_configuration = aws_launch_configuration.demo.id
+  max_size = 2
+  min_size = 1
+  name = "terraform-eks-demo"
+  # TF-UPGRADE-TODO: In Terraform v0.10 and earlier, it was sometimes necessary to
+  # force an interpolation expression to be interpreted as a list by wrapping it
+  # in an extra set of list brackets. That form was supported for compatibilty in
+  # v0.11, but is no longer supported in Terraform v0.12.
+  #
+  # If the expression in the following list itself returns a list, remove the
+  # brackets to avoid interpretation as a list of lists. If the expression
+  # returns a single list item then leave it as-is and remove this TODO comment.
+  vpc_zone_identifier = module.vpc.public_subnets
 
   tag {
-    key                 = "Name"
-    value               = "terraform-eks-demo"
+    key = "Name"
+    value = "terraform-eks-demo"
     propagate_at_launch = true
   }
 
   tag {
-    key                 = "kubernetes.io/cluster/${var.cluster-name}"
-    value               = "owned"
+    key = "kubernetes.io/cluster/${var.cluster-name}"
+    value = "owned"
     propagate_at_launch = true
   }
 }
+
diff --git a/eks-demo/external-ip.tf b/eks-demo/external-ip.tf
index c0fc52c..5f95350 100644
--- a/eks-demo/external-ip.tf
+++ b/eks-demo/external-ip.tf
@@ -5,3 +5,4 @@ data "http" "workstation-external-ip" {
 locals {
   workstation-external-cidr = "${chomp(data.http.workstation-external-ip.body)}/32"
 }
+
diff --git a/eks-demo/iam-workers.tf b/eks-demo/iam-workers.tf
index 9649735..4c88301 100644
--- a/eks-demo/iam-workers.tf
+++ b/eks-demo/iam-workers.tf
@@ -15,24 +15,26 @@ resource "aws_iam_role" "demo-node" {
   ]
 }
 POLICY
+
 }
 
 resource "aws_iam_role_policy_attachment" "demo-node-AmazonEKSWorkerNodePolicy" {
   policy_arn = "arn:aws:iam::aws:policy/AmazonEKSWorkerNodePolicy"
-  role       = "${aws_iam_role.demo-node.name}"
+  role = aws_iam_role.demo-node.name
 }
 
 resource "aws_iam_role_policy_attachment" "demo-node-AmazonEKS_CNI_Policy" {
   policy_arn = "arn:aws:iam::aws:policy/AmazonEKS_CNI_Policy"
-  role       = "${aws_iam_role.demo-node.name}"
+  role = aws_iam_role.demo-node.name
 }
 
 resource "aws_iam_role_policy_attachment" "demo-node-AmazonEC2ContainerRegistryReadOnly" {
   policy_arn = "arn:aws:iam::aws:policy/AmazonEC2ContainerRegistryReadOnly"
-  role       = "${aws_iam_role.demo-node.name}"
+  role = aws_iam_role.demo-node.name
 }
 
 resource "aws_iam_instance_profile" "demo-node" {
   name = "terraform-eks-demo"
-  role = "${aws_iam_role.demo-node.name}"
+  role = aws_iam_role.demo-node.name
 }
+
diff --git a/eks-demo/iam.tf b/eks-demo/iam.tf
index 629b147..6a34dc5 100644
--- a/eks-demo/iam.tf
+++ b/eks-demo/iam.tf
@@ -15,22 +15,23 @@ resource "aws_iam_role" "demo-cluster" {
   ]
 }
 POLICY
+
 }
 
 resource "aws_iam_role_policy_attachment" "demo-cluster-AmazonEKSClusterPolicy" {
   policy_arn = "arn:aws:iam::aws:policy/AmazonEKSClusterPolicy"
-  role       = "${aws_iam_role.demo-cluster.name}"
+  role = aws_iam_role.demo-cluster.name
 }
 
 resource "aws_iam_role_policy_attachment" "demo-cluster-AmazonEKSServicePolicy" {
   policy_arn = "arn:aws:iam::aws:policy/AmazonEKSServicePolicy"
-  role       = "${aws_iam_role.demo-cluster.name}"
+  role = aws_iam_role.demo-cluster.name
 }
 
 # If no loadbalancer was ever created in this region, then this following role is necessary
 resource "aws_iam_role_policy" "demo-cluster-service-linked-role" {
   name = "service-linked-role"
-  role = "${aws_iam_role.demo-cluster.name}"
+  role = aws_iam_role.demo-cluster.name
 
   policy = <<EOF
 {
@@ -51,4 +52,6 @@ resource "aws_iam_role_policy" "demo-cluster-service-linked-role" {
     ]
 }
 EOF
+
 }
+
diff --git a/eks-demo/outputs.tf b/eks-demo/outputs.tf
index a7b36f7..0575fd5 100644
--- a/eks-demo/outputs.tf
+++ b/eks-demo/outputs.tf
@@ -7,7 +7,7 @@ apiVersion: v1
 clusters:
 - cluster:
     server: ${aws_eks_cluster.demo.endpoint}
-    certificate-authority-data: ${aws_eks_cluster.demo.certificate_authority.0.data}
+    certificate-authority-data: ${aws_eks_cluster.demo.certificate_authority[0].data}
   name: kubernetes
 contexts:
 - context:
@@ -28,10 +28,11 @@ users:
         - "-i"
         - "${var.cluster-name}"
 KUBECONFIG
+
 }
 
 output "kubeconfig" {
-  value = "${local.kubeconfig}"
+  value = local.kubeconfig
 }
 
 # Join configuration
@@ -53,8 +54,10 @@ data:
         - system:bootstrappers
         - system:nodes
 CONFIGMAPAWSAUTH
+
 }
 
 output "config-map-aws-auth" {
-  value = "${local.config-map-aws-auth}"
+value = local.config-map-aws-auth
 }
+
diff --git a/eks-demo/providers.tf b/eks-demo/providers.tf
index 278152b..47fa6a3 100644
--- a/eks-demo/providers.tf
+++ b/eks-demo/providers.tf
@@ -1,10 +1,13 @@
 provider "aws" {
-  region  = "us-east-1"
+  region = "us-east-1"
 }
 
+data "aws_region" "current" {
+}
 
-data "aws_region" "current" {}
+data "aws_availability_zones" "available" {
+}
 
-data "aws_availability_zones" "available" {}
+provider "http" {
+}
 
-provider "http" {}
diff --git a/eks-demo/securitygroups-workers.tf b/eks-demo/securitygroups-workers.tf
index d6b26c8..11acf2e 100644
--- a/eks-demo/securitygroups-workers.tf
+++ b/eks-demo/securitygroups-workers.tf
@@ -2,7 +2,7 @@
 resource "aws_security_group" "demo-node" {
   name        = "terraform-eks-demo-node"
   description = "Security group for all nodes in the cluster"
-  vpc_id      = "${module.vpc.vpc_id}"
+  vpc_id      = module.vpc.vpc_id
 
   egress {
     from_port   = 0
@@ -11,20 +11,18 @@ resource "aws_security_group" "demo-node" {
     cidr_blocks = ["0.0.0.0/0"]
   }
 
-  tags = "${
-    map(
-     "Name", "terraform-eks-demo-node",
-     "kubernetes.io/cluster/${var.cluster-name}", "owned",
-    )
-  }"
+  tags = {
+    "Name"                                      = "terraform-eks-demo-node"
+    "kubernetes.io/cluster/${var.cluster-name}" = "owned"
+  }
 }
 
 resource "aws_security_group_rule" "demo-node-ingress-self" {
   description              = "Allow node to communicate with each other"
   from_port                = 0
   protocol                 = "-1"
-  security_group_id        = "${aws_security_group.demo-node.id}"
-  source_security_group_id = "${aws_security_group.demo-node.id}"
+  security_group_id        = aws_security_group.demo-node.id
+  source_security_group_id = aws_security_group.demo-node.id
   to_port                  = 65535
   type                     = "ingress"
 }
@@ -33,8 +31,8 @@ resource "aws_security_group_rule" "demo-node-ingress-cluster" {
   description              = "Allow worker Kubelets and pods to receive communication from the cluster control plane"
   from_port                = 1025
   protocol                 = "tcp"
-  security_group_id        = "${aws_security_group.demo-node.id}"
-  source_security_group_id = "${aws_security_group.demo-cluster.id}"
+  security_group_id        = aws_security_group.demo-node.id
+  source_security_group_id = aws_security_group.demo-cluster.id
   to_port                  = 65535
   type                     = "ingress"
 }
diff --git a/eks-demo/securitygroups.tf b/eks-demo/securitygroups.tf
index c75582a..504e78f 100644
--- a/eks-demo/securitygroups.tf
+++ b/eks-demo/securitygroups.tf
@@ -1,7 +1,7 @@
 resource "aws_security_group" "demo-cluster" {
   name        = "terraform-eks-demo-cluster"
   description = "Cluster communication with worker nodes"
-  vpc_id      = "${module.vpc.vpc_id}"
+  vpc_id      = module.vpc.vpc_id
 
   egress {
     from_port   = 0
@@ -10,7 +10,7 @@ resource "aws_security_group" "demo-cluster" {
     cidr_blocks = ["0.0.0.0/0"]
   }
 
-  tags {
+  tags = {
     Name = "terraform-eks-demo"
   }
 }
@@ -19,18 +19,26 @@ resource "aws_security_group_rule" "demo-cluster-ingress-node-https" {
   description              = "Allow pods to communicate with the cluster API Server"
   from_port                = 443
   protocol                 = "tcp"
-  security_group_id        = "${aws_security_group.demo-cluster.id}"
-  source_security_group_id = "${aws_security_group.demo-node.id}"
+  security_group_id        = aws_security_group.demo-cluster.id
+  source_security_group_id = aws_security_group.demo-node.id
   to_port                  = 443
   type                     = "ingress"
 }
 
 resource "aws_security_group_rule" "demo-cluster-ingress-workstation-https" {
-  cidr_blocks       = ["${local.workstation-external-cidr}"]
+  # TF-UPGRADE-TODO: In Terraform v0.10 and earlier, it was sometimes necessary to
+  # force an interpolation expression to be interpreted as a list by wrapping it
+  # in an extra set of list brackets. That form was supported for compatibilty in
+  # v0.11, but is no longer supported in Terraform v0.12.
+  #
+  # If the expression in the following list itself returns a list, remove the
+  # brackets to avoid interpretation as a list of lists. If the expression
+  # returns a single list item then leave it as-is and remove this TODO comment.
+  cidr_blocks       = [local.workstation-external-cidr]
   description       = "Allow workstation to communicate with the cluster API Server"
   from_port         = 443
   protocol          = "tcp"
-  security_group_id = "${aws_security_group.demo-cluster.id}"
+  security_group_id = aws_security_group.demo-cluster.id
   to_port           = 443
   type              = "ingress"
 }
diff --git a/eks-demo/vars.tf b/eks-demo/vars.tf
index fd50e18..8dec856 100644
--- a/eks-demo/vars.tf
+++ b/eks-demo/vars.tf
@@ -1,4 +1,5 @@
 variable "cluster-name" {
   default = "terraform-eks-demo"
-  type    = "string"
+  type    = string
 }
+
diff --git a/eks-demo/versions.tf b/eks-demo/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/eks-demo/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/eks-demo/vpc.tf b/eks-demo/vpc.tf
index 38b9093..288e8c8 100644
--- a/eks-demo/vpc.tf
+++ b/eks-demo/vpc.tf
@@ -1,22 +1,20 @@
 module "vpc" {
-  source = "terraform-aws-modules/vpc/aws"
-  version = "~> v1.0"
+  source  = "terraform-aws-modules/vpc/aws"
+  version = "2.6.0"
 
   name = "vpc-module-demo"
   cidr = "10.0.0.0/16"
 
-  azs             = ["${slice(data.aws_availability_zones.available.names, 0, 3)}"]
+  azs             = slice(data.aws_availability_zones.available.names, 0, 3)
   private_subnets = ["10.0.1.0/24", "10.0.2.0/24", "10.0.3.0/24"]
   public_subnets  = ["10.0.101.0/24", "10.0.102.0/24", "10.0.103.0/24"]
 
   enable_nat_gateway = false
   enable_vpn_gateway = false
 
-  tags = "${
-    map(
-     "Name", "terraform-eks-demo-node",
-     "kubernetes.io/cluster/${var.cluster-name}", "shared",
-    )
-  }"
+  tags = {
+    "Name"                                      = "terraform-eks-demo-node"
+    "kubernetes.io/cluster/${var.cluster-name}" = "shared"
+  }
 }
 
diff --git a/first-steps/instance.tf b/first-steps/instance.tf
index de3e4c5..8ab8840 100644
--- a/first-steps/instance.tf
+++ b/first-steps/instance.tf
@@ -8,3 +8,4 @@ resource "aws_instance" "example" {
   ami           = "ami-0d729a60"
   instance_type = "t2.micro"
 }
+
diff --git a/first-steps/versions.tf b/first-steps/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/first-steps/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/jenkins-packer-demo/amivar.tf b/jenkins-packer-demo/amivar.tf
index 3503935..f007f81 100644
--- a/jenkins-packer-demo/amivar.tf
+++ b/jenkins-packer-demo/amivar.tf
@@ -1 +1,4 @@
-variable "APP_INSTANCE_AMI" { default = "" }
+variable "APP_INSTANCE_AMI" {
+  default = ""
+}
+
diff --git a/jenkins-packer-demo/cloudinit.tf b/jenkins-packer-demo/cloudinit.tf
index f6cdfec..359df49 100644
--- a/jenkins-packer-demo/cloudinit.tf
+++ b/jenkins-packer-demo/cloudinit.tf
@@ -1,19 +1,19 @@
 data "template_file" "jenkins-init" {
-  template = "${file("scripts/jenkins-init.sh")}"
-  vars {
-    DEVICE = "${var.INSTANCE_DEVICE_NAME}"
-    JENKINS_VERSION = "${var.JENKINS_VERSION}"
-    TERRAFORM_VERSION = "${var.TERRAFORM_VERSION}"
+  template = file("scripts/jenkins-init.sh")
+  vars = {
+    DEVICE            = var.INSTANCE_DEVICE_NAME
+    JENKINS_VERSION   = var.JENKINS_VERSION
+    TERRAFORM_VERSION = var.TERRAFORM_VERSION
   }
 }
-data "template_cloudinit_config" "cloudinit-jenkins" {
 
-  gzip = false
+data "template_cloudinit_config" "cloudinit-jenkins" {
+  gzip          = false
   base64_encode = false
 
   part {
     content_type = "text/x-shellscript"
-    content      = "${data.template_file.jenkins-init.rendered}"
+    content      = data.template_file.jenkins-init.rendered
   }
-
 }
+
diff --git a/jenkins-packer-demo/instance.tf b/jenkins-packer-demo/instance.tf
index dcbec06..acba254 100644
--- a/jenkins-packer-demo/instance.tf
+++ b/jenkins-packer-demo/instance.tf
@@ -1,48 +1,48 @@
 resource "aws_instance" "jenkins-instance" {
-  ami           = "${lookup(var.AMIS, var.AWS_REGION)}"
+  ami           = var.AMIS[var.AWS_REGION]
   instance_type = "t2.small"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.jenkins-securitygroup.id}"]
+  vpc_security_group_ids = [aws_security_group.jenkins-securitygroup.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 
   # user data
-  user_data = "${data.template_cloudinit_config.cloudinit-jenkins.rendered}"
-
+  user_data = data.template_cloudinit_config.cloudinit-jenkins.rendered
 }
 
 resource "aws_ebs_volume" "jenkins-data" {
-    availability_zone = "eu-west-1a"
-    size = 20
-    type = "gp2" 
-    tags {
-        Name = "jenkins-data"
-    }
+  availability_zone = "eu-west-1a"
+  size              = 20
+  type              = "gp2"
+  tags = {
+    Name = "jenkins-data"
+  }
 }
 
 resource "aws_volume_attachment" "jenkins-data-attachment" {
-  device_name = "${var.INSTANCE_DEVICE_NAME}"
-  volume_id = "${aws_ebs_volume.jenkins-data.id}"
-  instance_id = "${aws_instance.jenkins-instance.id}"
+  device_name  = var.INSTANCE_DEVICE_NAME
+  volume_id    = aws_ebs_volume.jenkins-data.id
+  instance_id  = aws_instance.jenkins-instance.id
   skip_destroy = true
 }
 
 resource "aws_instance" "app-instance" {
-  count = "${var.APP_INSTANCE_COUNT}"
-  ami = "${var.APP_INSTANCE_AMI}"
+  count         = var.APP_INSTANCE_COUNT
+  ami           = var.APP_INSTANCE_AMI
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.app-securitygroup.id}"]
+  vpc_security_group_ids = [aws_security_group.app-securitygroup.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 }
+
diff --git a/jenkins-packer-demo/key.tf b/jenkins-packer-demo/key.tf
index 278a5a9..b41e059 100644
--- a/jenkins-packer-demo/key.tf
+++ b/jenkins-packer-demo/key.tf
@@ -1,7 +1,8 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
   lifecycle {
-    ignore_changes = ["public_key"]
+    ignore_changes = [public_key]
   }
 }
+
diff --git a/jenkins-packer-demo/output.tf b/jenkins-packer-demo/output.tf
index 1a3f26e..d5b4674 100644
--- a/jenkins-packer-demo/output.tf
+++ b/jenkins-packer-demo/output.tf
@@ -1,6 +1,8 @@
 output "jenkins-ip" {
-  value = ["${aws_instance.jenkins-instance.*.public_ip}"]
+  value = [aws_instance.jenkins-instance.*.public_ip]
 }
+
 output "app-ip" {
-  value = ["${aws_instance.app-instance.*.public_ip}"]
+  value = [aws_instance.app-instance.*.public_ip]
 }
+
diff --git a/jenkins-packer-demo/provider.tf b/jenkins-packer-demo/provider.tf
index ded6d8c..7925c73 100644
--- a/jenkins-packer-demo/provider.tf
+++ b/jenkins-packer-demo/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/jenkins-packer-demo/s3.tf b/jenkins-packer-demo/s3.tf
index a24b989..1696736 100644
--- a/jenkins-packer-demo/s3.tf
+++ b/jenkins-packer-demo/s3.tf
@@ -1,8 +1,9 @@
 resource "aws_s3_bucket" "terraform-state" {
-    bucket = "terraform-state-a2b621f"
-    acl = "private"
+  bucket = "terraform-state-a2b621f"
+  acl    = "private"
 
-    tags {
-        Name = "Terraform state"
-    }
+  tags = {
+    Name = "Terraform state"
+  }
 }
+
diff --git a/jenkins-packer-demo/securitygroup.tf b/jenkins-packer-demo/securitygroup.tf
index ad704d5..106f761 100644
--- a/jenkins-packer-demo/securitygroup.tf
+++ b/jenkins-packer-demo/securitygroup.tf
@@ -1,54 +1,56 @@
 resource "aws_security_group" "jenkins-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "jenkins-securitygroup"
+  vpc_id      = aws_vpc.main.id
+  name        = "jenkins-securitygroup"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
   ingress {
-      from_port = 8080
-      to_port = 8080
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 8080
+    to_port     = 8080
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "jenkins-securitygroup"
   }
 }
+
 resource "aws_security_group" "app-securitygroup" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "app-securitygroup"
+  vpc_id      = aws_vpc.main.id
+  name        = "app-securitygroup"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
   ingress {
-      from_port = 80
-      to_port = 80
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 80
+    to_port     = 80
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "app-securitygroup"
   }
 }
+
diff --git a/jenkins-packer-demo/vars.tf b/jenkins-packer-demo/vars.tf
index fadd498..4fb4501 100644
--- a/jenkins-packer-demo/vars.tf
+++ b/jenkins-packer-demo/vars.tf
@@ -1,26 +1,32 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
 variable "AMIS" {
-  type = "map"
+  type = map(string)
   default = {
     us-east-1 = "ami-13be557e"
     us-west-2 = "ami-06b94666"
     eu-west-1 = "ami-844e0bf7"
   }
 }
+
 variable "INSTANCE_DEVICE_NAME" {
   default = "/dev/xvdh"
 }
+
 variable "JENKINS_VERSION" {
   default = "2.121.2"
 }
+
 variable "TERRAFORM_VERSION" {
   default = "0.11.7"
 }
@@ -28,3 +34,4 @@ variable "TERRAFORM_VERSION" {
 variable "APP_INSTANCE_COUNT" {
   default = "0"
 }
+
diff --git a/jenkins-packer-demo/versions.tf b/jenkins-packer-demo/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/jenkins-packer-demo/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/jenkins-packer-demo/vpc.tf b/jenkins-packer-demo/vpc.tf
index 1325feb..4e9d809 100644
--- a/jenkins-packer-demo/vpc.tf
+++ b/jenkins-packer-demo/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+
diff --git a/module-demo/ecs.tf b/module-demo/ecs.tf
index 432fed2..53a91d9 100644
--- a/module-demo/ecs.tf
+++ b/module-demo/ecs.tf
@@ -1,49 +1,54 @@
-data "aws_caller_identity" "current" {}
+data "aws_caller_identity" "current" {
+}
 
 module "my-ecs" {
-  source         = "github.com/in4it/terraform-modules//modules/ecs-cluster?ref=v1.0.0"
-  VPC_ID         = "${module.vpc.vpc_id}"
+  source         = "github.com/in4it/terraform-modules//modules/ecs-cluster?ref=terraform-0.12"
+  VPC_ID         = module.vpc.vpc_id
   CLUSTER_NAME   = "my-ecs"
   INSTANCE_TYPE  = "t2.small"
-  SSH_KEY_NAME   = "${aws_key_pair.mykeypair.key_name}"
-  VPC_SUBNETS    = "${join(",", module.vpc.public_subnets)}"
+  SSH_KEY_NAME   = aws_key_pair.mykeypair.key_name
+  VPC_SUBNETS    = join(",", module.vpc.public_subnets)
   ENABLE_SSH     = true
-  SSH_SG         = "${aws_security_group.allow-ssh.id}"
+  SSH_SG         = aws_security_group.allow-ssh.id
   LOG_GROUP      = "my-log-group"
-  AWS_ACCOUNT_ID = "${data.aws_caller_identity.current.account_id}"
-  AWS_REGION     = "${var.AWS_REGION}"
+  AWS_ACCOUNT_ID = data.aws_caller_identity.current.account_id
+  AWS_REGION     = var.AWS_REGION
 }
+
 module "my-service" {
-  source              = "github.com/in4it/terraform-modules//modules/ecs-service?ref=v1.0.0"
-  VPC_ID              = "${module.vpc.vpc_id}"
+  source              = "github.com/in4it/terraform-modules//modules/ecs-service?ref=terraform-0.12"
+  VPC_ID              = module.vpc.vpc_id
   APPLICATION_NAME    = "my-service"
   APPLICATION_PORT    = "80"
   APPLICATION_VERSION = "latest"
-  CLUSTER_ARN         = "${module.my-ecs.cluster_arn}"
-  SERVICE_ROLE_ARN    = "${module.my-ecs.service_role_arn}"
-  AWS_REGION          = "${var.AWS_REGION}"
+  CLUSTER_ARN         = module.my-ecs.cluster_arn
+  SERVICE_ROLE_ARN    = module.my-ecs.service_role_arn
+  AWS_REGION          = var.AWS_REGION
   HEALTHCHECK_MATCHER = "200"
   CPU_RESERVATION     = "256"
   MEMORY_RESERVATION  = "128"
   LOG_GROUP           = "my-log-group"
   DESIRED_COUNT       = 2
-  ALB_ARN             = "${module.my-alb.alb_arn}"
+  ALB_ARN             = module.my-alb.alb_arn
 }
+
 module "my-alb" {
-  source             = "github.com/in4it/terraform-modules//modules/alb?ref=v1.0.0"
-  VPC_ID             = "${module.vpc.vpc_id}"
+  source             = "github.com/in4it/terraform-modules//modules/alb?ref=terraform-0.12"
+  VPC_ID             = module.vpc.vpc_id
   ALB_NAME           = "my-alb"
-  VPC_SUBNETS        = "${join(",", module.vpc.public_subnets)}"
-  DEFAULT_TARGET_ARN = "${module.my-service.target_group_arn}"
+  VPC_SUBNETS        = join(",", module.vpc.public_subnets)
+  DEFAULT_TARGET_ARN = module.my-service.target_group_arn
   DOMAIN             = "*.ecs.newtech.academy"
   INTERNAL           = false
-  ECS_SG             = "${module.my-ecs.cluster_sg}"
+  ECS_SG             = module.my-ecs.cluster_sg
 }
+
 module "my-alb-rule" {
-  source             = "github.com/in4it/terraform-modules//modules/alb-rule?ref=v1.0.0"
-  LISTENER_ARN       = "${module.my-alb.http_listener_arn}"
-  PRIORITY           = 100
-  TARGET_GROUP_ARN   = "${module.my-service.target_group_arn}"
-  CONDITION_FIELD    = "host-header"
-  CONDITION_VALUES   = ["subdomain.ecs.newtech.academy"]
+  source           = "github.com/in4it/terraform-modules//modules/alb-rule?ref=terraform-0.12"
+  LISTENER_ARN     = module.my-alb.http_listener_arn
+  PRIORITY         = 100
+  TARGET_GROUP_ARN = module.my-service.target_group_arn
+  CONDITION_FIELD  = "host-header"
+  CONDITION_VALUES = ["subdomain.ecs.newtech.academy"]
 }
+
diff --git a/module-demo/key.tf b/module-demo/key.tf
index 2b92f43..58b093f 100644
--- a/module-demo/key.tf
+++ b/module-demo/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
   key_name   = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/module-demo/provider.tf b/module-demo/provider.tf
index 6b43802..6a26783 100644
--- a/module-demo/provider.tf
+++ b/module-demo/provider.tf
@@ -1,3 +1,4 @@
 provider "aws" {
-  region  = "eu-west-1"
+  region = "eu-west-1"
 }
+
diff --git a/module-demo/securitygroup.tf b/module-demo/securitygroup.tf
index 9cb4d90..1bf7d90 100644
--- a/module-demo/securitygroup.tf
+++ b/module-demo/securitygroup.tf
@@ -1,5 +1,5 @@
 resource "aws_security_group" "allow-ssh" {
-  vpc_id      = "${module.vpc.vpc_id}"
+  vpc_id      = module.vpc.vpc_id
   name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
 
@@ -17,7 +17,8 @@ resource "aws_security_group" "allow-ssh" {
     cidr_blocks = ["0.0.0.0/0"]
   }
 
-  tags {
+  tags = {
     Name = "allow-ssh"
   }
 }
+
diff --git a/module-demo/versions.tf b/module-demo/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/module-demo/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/module-demo/vpc.tf b/module-demo/vpc.tf
index 728b1fe..f3d3311 100644
--- a/module-demo/vpc.tf
+++ b/module-demo/vpc.tf
@@ -1,5 +1,6 @@
 module "vpc" {
-  source = "terraform-aws-modules/vpc/aws"
+  source  = "terraform-aws-modules/vpc/aws"
+  version = "2.7.0"
 
   name = "vpc-module-demo"
   cidr = "10.0.0.0/16"
@@ -16,3 +17,4 @@ module "vpc" {
     Environment = "prod"
   }
 }
+
diff --git a/packer-demo/instance.tf b/packer-demo/instance.tf
index 76dc9da..7283077 100644
--- a/packer-demo/instance.tf
+++ b/packer-demo/instance.tf
@@ -1,13 +1,14 @@
 resource "aws_instance" "example" {
-  ami           = "${var.AMI_ID}"
+  ami           = var.AMI_ID
   instance_type = "t2.micro"
 
   # the VPC subnet
-  subnet_id = "${aws_subnet.main-public-1.id}"
+  subnet_id = aws_subnet.main-public-1.id
 
   # the security group
-  vpc_security_group_ids = ["${aws_security_group.example-instance.id}"]
+  vpc_security_group_ids = [aws_security_group.example-instance.id]
 
   # the public SSH key
-  key_name = "${aws_key_pair.mykeypair.key_name}"
+  key_name = aws_key_pair.mykeypair.key_name
 }
+
diff --git a/packer-demo/key.tf b/packer-demo/key.tf
index 0d3c220..58b093f 100644
--- a/packer-demo/key.tf
+++ b/packer-demo/key.tf
@@ -1,4 +1,5 @@
 resource "aws_key_pair" "mykeypair" {
-  key_name = "mykeypair"
-  public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
+  key_name   = "mykeypair"
+  public_key = file(var.PATH_TO_PUBLIC_KEY)
 }
+
diff --git a/packer-demo/provider.tf b/packer-demo/provider.tf
index ded6d8c..7925c73 100644
--- a/packer-demo/provider.tf
+++ b/packer-demo/provider.tf
@@ -1,3 +1,4 @@
-provider "aws" { 
-    region = "${var.AWS_REGION}"
+provider "aws" {
+  region = var.AWS_REGION
 }
+
diff --git a/packer-demo/securitygroup.tf b/packer-demo/securitygroup.tf
index b796e18..fd476e9 100644
--- a/packer-demo/securitygroup.tf
+++ b/packer-demo/securitygroup.tf
@@ -1,21 +1,21 @@
 resource "aws_security_group" "example-instance" {
-  vpc_id = "${aws_vpc.main.id}"
-  name = "allow-ssh"
+  vpc_id      = aws_vpc.main.id
+  name        = "allow-ssh"
   description = "security group that allows ssh and all egress traffic"
   egress {
-      from_port = 0
-      to_port = 0
-      protocol = "-1"
-      cidr_blocks = ["0.0.0.0/0"]
+    from_port   = 0
+    to_port     = 0
+    protocol    = "-1"
+    cidr_blocks = ["0.0.0.0/0"]
   }
 
   ingress {
-      from_port = 22
-      to_port = 22
-      protocol = "tcp"
-      cidr_blocks = ["0.0.0.0/0"]
-  } 
-tags {
+    from_port   = 22
+    to_port     = 22
+    protocol    = "tcp"
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+  tags = {
     Name = "example-instance"
   }
 }
diff --git a/packer-demo/vars.tf b/packer-demo/vars.tf
index ce2e56b..3878f40 100644
--- a/packer-demo/vars.tf
+++ b/packer-demo/vars.tf
@@ -1,9 +1,12 @@
 variable "AWS_REGION" {
   default = "eu-west-1"
 }
+
 variable "PATH_TO_PRIVATE_KEY" {
   default = "mykey"
 }
+
 variable "PATH_TO_PUBLIC_KEY" {
   default = "mykey.pub"
 }
+
diff --git a/packer-demo/versions.tf b/packer-demo/versions.tf
new file mode 100644
index 0000000..ac97c6a
--- /dev/null
+++ b/packer-demo/versions.tf
@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}
diff --git a/packer-demo/vpc.tf b/packer-demo/vpc.tf
index 1325feb..4e9d809 100644
--- a/packer-demo/vpc.tf
+++ b/packer-demo/vpc.tf
@@ -1,110 +1,117 @@
 # Internet VPC
 resource "aws_vpc" "main" {
-    cidr_block = "10.0.0.0/16"
-    instance_tenancy = "default"
-    enable_dns_support = "true"
-    enable_dns_hostnames = "true"
-    enable_classiclink = "false"
-    tags {
-        Name = "main"
-    }
+  cidr_block           = "10.0.0.0/16"
+  instance_tenancy     = "default"
+  enable_dns_support   = "true"
+  enable_dns_hostnames = "true"
+  enable_classiclink   = "false"
+  tags = {
+    Name = "main"
+  }
 }
 
-
 # Subnets
 resource "aws_subnet" "main-public-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.1.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.1.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
+
 resource "aws_subnet" "main-public-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.2.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.2.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-public-2"
-    }
+  tags = {
+    Name = "main-public-2"
+  }
 }
+
 resource "aws_subnet" "main-public-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.3.0/24"
-    map_public_ip_on_launch = "true"
-    availability_zone = "eu-west-1c"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.3.0/24"
+  map_public_ip_on_launch = "true"
+  availability_zone       = "eu-west-1c"
 
-    tags {
-        Name = "main-public-3"
-    }
+  tags = {
+    Name = "main-public-3"
+  }
 }
+
 resource "aws_subnet" "main-private-1" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.4.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1a"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.4.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1a"
 
-    tags {
-        Name = "main-private-1"
-    }
+  tags = {
+    Name = "main-private-1"
+  }
 }
+
 resource "aws_subnet" "main-private-2" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.5.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1b"
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.5.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1b"
 
-    tags {
-        Name = "main-private-2"
-    }
+  tags = {
+    Name = "main-private-2"
+  }
 }
-resource "aws_subnet" "main-private-3" {
-    vpc_id = "${aws_vpc.main.id}"
-    cidr_block = "10.0.6.0/24"
-    map_public_ip_on_launch = "false"
-    availability_zone = "eu-west-1c"
 
-    tags {
-        Name = "main-private-3"
-    }
+resource "aws_subnet" "main-private-3" {
+  vpc_id                  = aws_vpc.main.id
+  cidr_block              = "10.0.6.0/24"
+  map_public_ip_on_launch = "false"
+  availability_zone       = "eu-west-1c"
+
+  tags = {
+    Name = "main-private-3"
+  }
 }
 
 # Internet GW
 resource "aws_internet_gateway" "main-gw" {
-    vpc_id = "${aws_vpc.main.id}"
+  vpc_id = aws_vpc.main.id
 
-    tags {
-        Name = "main"
-    }
+  tags = {
+    Name = "main"
+  }
 }
 
 # route tables
 resource "aws_route_table" "main-public" {
-    vpc_id = "${aws_vpc.main.id}"
-    route {
-        cidr_block = "0.0.0.0/0"
-        gateway_id = "${aws_internet_gateway.main-gw.id}"
-    }
+  vpc_id = aws_vpc.main.id
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = aws_internet_gateway.main-gw.id
+  }
 
-    tags {
-        Name = "main-public-1"
-    }
+  tags = {
+    Name = "main-public-1"
+  }
 }
 
 # route associations public
 resource "aws_route_table_association" "main-public-1-a" {
-    subnet_id = "${aws_subnet.main-public-1.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-1.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-2-a" {
-    subnet_id = "${aws_subnet.main-public-2.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-2.id
+  route_table_id = aws_route_table.main-public.id
 }
+
 resource "aws_route_table_association" "main-public-3-a" {
-    subnet_id = "${aws_subnet.main-public-3.id}"
-    route_table_id = "${aws_route_table.main-public.id}"
+  subnet_id      = aws_subnet.main-public-3.id
+  route_table_id = aws_route_table.main-public.id
 }
+