Terraform AWS VPC-Subnets Module

This repository contains a Terraform module for creating and managing AWS VPC networks, including subnets, Internet Gateways, Network ACLs, and NAT Gateways.

Usage

• Terraform module to create VPC subnets.
• Module source: app.terraform.io/subhamay-bhattacharyya/vpc-subnets/aws
• Version: 1.0.0

Required Inputs:

• project-name: The name of the project.
• vpc-cidr: The CIDR block for the VPC (e.g., "10.0.0.0/16").
• enable-dns-hostnames: Boolean to enable/disable DNS hostnames in the VPC.
• enable-dns-support: Boolean to enable/disable DNS support in the VPC.
• subnet-configuration: A map defining the CIDR blocks for public and private subnets.
• ci-build: A string representing the CI build identifier.

Example Usage:

module "vpc_subnets" {
  source  = "app.terraform.io/subhamay-bhattacharyya/vpc-subnets/aws"
  version = "1.0.0"

  project-name             = "your-project-name"
  vpc-cidr                 = "your-vpc-cidr-range"
  subnet-configuration     = "your-subnet-configuration"
  ci-build                 = "your-ci-build-string"
}

Subnet configuration

Configure the numbers of public and private subnets using the variables.

public-subnet-count  = 1
private-subnet-count = 1

Use local variables to configure the subnet CIDR blocks

locals {
  public-cidrs  = var.public-subnet-count > 0 ? [for i in range(0, var.public-subnet-count * 2 - 1, 2) : cidrsubnet(var.vpc-cidr, 8, i)] : []
  private-cidrs = var.private-subnet-count > 0 ? [for i in range(1, var.private-subnet-count * 2, 2) : cidrsubnet(var.vpc-cidr, 8, i)] : []
}

locals {
  subnet-configuration = {
    public  = local.public-cidrs
    private = local.private-cidrs
  }
}

DNS hostname and DNS support

DNS hostname and DNS support are enabled by default. To override the default values, use false in the .tfvars file

Default tags

Use local variables to configure the default tags. The default resource tags are implemented using the CI/CD Pipeline. The following mao just refers to it.

locals {
  tags = {
    Environment      = var.environment-name
    ProjectName      = var.project-name
    GitHubRepository = var.github-repo
    GitHubRef        = var.github-ref
    GitHubURL        = var.github-url
    GitHubSHA        = var.github-sha
  }
}

Note

• To create only public subnets only pass private-subnet-count=0
• To create only private subnets only pass public-subnet-count=0
• Internet gateway will be created only if atleast one public subnet is created.

Inputs

Name	Description	Type	Default	Required
project-name	The name of the project	string	n/a	yes
vpc-cidr	The CIDR block for the VPC	string	10.0.0.0/16	yes
enable-dns-hostnames	Boolean to enable/disable DNS hostnames in the VPC	bool	true	no
enable-dns-support	Boolean to enable/disable DNS support in the VPC	bool	true	no
subnet-configuration	A map defining the CIDR blocks for public and private subnets	map	n/a	yes
ci-build	A string representing the CI build identifier	string	""	yes

Subnet Configuration Input (Map)

Name	Description	Type	Default	Required
public	The CIDR blocks for the public subnets	list	n/a	yes
private	The CIDR blocks for the private subnets	list	n/a	yes

Outputs

Name	Description
az-list	The list of availability zones in the region
vpc-id	VPC Id
subnet-configuration	Configuration for public and private subnets
internet-gateway-id	The ID of the Internet Gateway
public-subnet-ids	The IDs of the public subnets
private-subnet-ids	The IDs of the private subnets
public-route-table-ids	The IDs of the public route tables
private-route-table-ids	The IDs of the private route tables
network-acl-id	The ID of the Network ACL
public-nacl-ids	The IDs of the public network ACL associations
private-nacl-ids	The IDs of the private network ACL associations