Added data vpc in scenario that VPC is already created for you

Author: ryanoolala

main.tf

@@ -8,14 +8,19 @@ locals {
   nat_gateway_count = var.single_nat_gateway ? 1 : var.one_nat_gateway_per_az ? length(var.azs) : local.max_subnet_length
 
   # Use `local.vpc_id` to give a hint to Terraform that subnets should be deleted before secondary CIDR blocks can be free!
-  vpc_id = element(
+  vpc_id = var.create_vpc ? element(
     concat(
       aws_vpc_ipv4_cidr_block_association.this.*.vpc_id,
       aws_vpc.this.*.id,
       [""],
     ),
     0,
-  )
+  ) : data.aws_vpc.vpc.id
+}
+
+data "aws_vpc" "vpc" {
+  count = var.create_vpc ? 0 : 1
+  id = var.vpc_id
 }
 
 ######

variables.tf

@@ -4,6 +4,12 @@ variable "create_vpc" {
   default     = true
 }
 
+variable "vpc_id" {
+  description = "VPC id for use in cases where VPC was already created and you would like to reuse it with this module. Not required if create_vpc = true"
+  type = string
+  default = ""
+}
+
 variable "name" {
   description = "Name to be used on all the resources as identifier"
   default     = ""