Terraform 0.12 (#20)

* Terraform 0.12

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"
 }