Guidelines

This Terraform module provides a slightly opinionated AWS VPC implementation that can be invoked as follows:

module "vpc" {
  source               = "github.com/CloudPartners/terraform_aws_vpc"
  cidr                 = "${var.vpc_cidr}"
  enable_dns_hostnames = true
  environment          = "${var.environment}"

  tags {
    CostCentre  = "VPC"
    Environment = "${var.environment}"
  }

  igw_tags {
    CostCentre  = "IGW"
    Environment = "${var.environment}"
  }  
}

The opinionated bit is in reference to the subnets / cidr blocks that are created. The following table shows the assumed conventions, based on the CIDR block specified for the VPC. The AZ alternates between the first two AZs in the Region defined by the AWS provider in the calling template. Public subnets are set to auto-assign Public IP addresses.

Subnet	Type	AZ	CIDR
Public 1	PUBLIC	0	cidrsubnet(var.cidr, 8, 0)
Public 2	PUBLIC	1	cidrsubnet(var.cidr, 8, 100)
Web 1	PRIVATE	0	cidrsubnet(var.cidr, 8, 10)
Web 2	PRIVATE	1	cidrsubnet(var.cidr, 8, 110)
Services 1	PRIVATE	0	cidrsubnet(var.cidr, 8, 20)
Services 2	PRIVATE	1	cidrsubnet(var.cidr, 8, 120)
Cache 1	PRIVATE	0	cidrsubnet(var.cidr, 8, 30)
Cache 2	PRIVATE	1	cidrsubnet(var.cidr, 8, 130)
Data 1	PRIVATE	0	cidrsubnet(var.cidr, 8, 40)
Data 2	PRIVATE	1	cidrsubnet(var.cidr, 8, 140)

Inputs

The following input variables can be specified:

Variable	Description	Required	Default
cidr	The CIDR block for the VPC	Y	-
enable_dns_support	Boolean flag to enable/disable DNS support in the VPC	N	true
enable_dns_hostnames	Boolean flag to enable/disable DNS hostnames in the VPC	N	false
environment	General environment name - used in generated tag mappings and naming of resources	Y	-
tags	Generic tag map to inject into resources in this module	N	{}
igw_tags	Generic tag map to inject into IGW resources in this module	N	{}

Outputs

The following output variables are provided:

Variable	Description
vpc_id	The ID of the new AWS VPC
public_subnet_ids	List of 'Public x' subnet IDs (see above)
public_subnet_cidr_blocks	List of 'Public x' subnet CIDR blocks (see above)
public_subnet_azs	List of 'Public x' subnet AZs (see above)
web_subnet_ids	List of 'Web x' subnet IDs (see above)
web_subnet_cidr_blocks	List of 'Web x' subnet CIDR blocks (see above)
web_subnet_azs	List of 'Web x' subnet AZs (see above)
services_subnet_ids	List of 'Services x' subnet IDs (see above)
services_subnet_cidr_blocks	List of 'Services x' subnet CIDR blocks (see above)
services_subnet_azs	List of 'Services x' subnet AZs (see above)
cache_subnet_ids	List of 'Cache x' subnet IDs (see above)
cache_subnet_cidr_blocks	List of 'Cache x' subnet CIDR blocks (see above)
cache_subnet_azs	List of 'Cache x' subnet AZs (see above)
data_subnet_ids	List of 'Data x' subnet IDs (see above)
data_subnet_cidr_blocks	List of 'Data x' subnet CIDR blocks (see above)
data_subnet_azs	List of 'Data x' subnet AZs (see above)