Add support for specifying AZ in VPN Gateway (#401)

README.md

@@ -528,6 +528,7 @@ It is possible to integrate this VPC module with [terraform-aws-transit-gateway
 | vpc\_endpoint\_tags | Additional tags for the VPC Endpoints | `map(string)` | `{}` | no |
 | vpc\_flow\_log\_tags | Additional tags for the VPC Flow Logs | `map(string)` | `{}` | no |
 | vpc\_tags | Additional tags for the VPC | `map(string)` | `{}` | no |
+| vpn\_gateway\_az | The Availability Zone for the VPN Gateway | `string` | n/a | yes |
 | vpn\_gateway\_id | ID of VPN Gateway to attach to the VPC | `string` | `""` | no |
 | vpn\_gateway\_tags | Additional tags for the VPN gateway | `map(string)` | `{}` | no |
 

main.tf

@@ -1020,8 +1020,9 @@ resource "aws_customer_gateway" "this" {
 resource "aws_vpn_gateway" "this" {
   count = var.create_vpc && var.enable_vpn_gateway ? 1 : 0
 
-  vpc_id          = local.vpc_id
-  amazon_side_asn = var.amazon_side_asn
+  vpc_id            = local.vpc_id
+  amazon_side_asn   = var.amazon_side_asn
+  availability_zone = var.vpn_gateway_az
 
   tags = merge(
     {

variables.tf

@@ -1327,6 +1327,12 @@ variable "amazon_side_asn" {
   default     = "64512"
 }
 
+variable "vpn_gateway_az" {
+  description = "The Availability Zone for the VPN Gateway"
+  type        = string
+  default     = null
+}
+
 variable "propagate_private_route_tables_vgw" {
   description = "Should be true if you want route table propagation"
   type        = bool