Terraform 0.12 (#20)

* Terraform 0.12

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"
 }
+