Title: Update quoted type constraints to compliance with Terraform 0.15.3

aws/aws_reverse_proxy/certificate.tf

@@ -1,7 +1,7 @@
 # Generate a certificate for the domain automatically using ACM
 # https://www.terraform.io/docs/providers/aws/r/acm_certificate.html
 resource "aws_acm_certificate" "this" {
-  provider          = "aws.us_east_1"                                                              # because ACM is only available in the "us-east-1" region
+  provider          = aws.us_east_1                                                              # because ACM is only available in the "us-east-1" region
   domain_name       = "${var.site_domain}"
   validation_method = "DNS"                                                                        # the required records are created below
   tags              = "${merge(var.tags, map("Name", "${var.comment_prefix}${var.site_domain}"))}"

aws/aws_reverse_proxy/variables.tf

@@ -38,7 +38,7 @@ variable "default_root_object" {
 
 variable "add_response_headers" {
   description = "Map of HTTP headers (if any) to add to outgoing responses before sending them to clients"
-  type        = "map"
+  type        = map(string)
 
   default = {
     "Strict-Transport-Security" = "max-age=31557600; preload" # i.e. 1 year (in seconds)
@@ -105,7 +105,7 @@ variable "lambda_logging_enabled" {
 
 variable "tags" {
   description = "AWS Tags to add to all resources created (where possible); see https://aws.amazon.com/answers/account-management/aws-tagging-strategies/"
-  type        = "map"
+  type        = map(string)
   default     = {}
 }
 

aws/aws_static_site/variables.tf

@@ -39,7 +39,7 @@ variable "default_root_object" {
 
 variable "add_response_headers" {
   description = "Map of HTTP headers (if any) to add to outgoing responses before sending them to clients"
-  type        = "map"
+  type        = map(string)
 
   default = {
     "Strict-Transport-Security" = "max-age=31557600; preload" # i.e. 1 year (in seconds)
@@ -73,7 +73,7 @@ variable "lambda_logging_enabled" {
 
 variable "tags" {
   description = "AWS Tags to add to all resources created (where possible); see https://aws.amazon.com/answers/account-management/aws-tagging-strategies/"
-  type        = "map"
+  type        = map(string)
   default     = {}
 }