3-Tier AWS VPC with NAT Gateways using Terraform

Introduction

!! This repo is ONLY for learning purposes. You must provide YOUR own AWS Credentials in order to use the Terraform configuration !!

Download the repository

• Learn about Terraform Registry and Modules
• Learn about VPC Module

Executing Terraform Commands

# Terraform Initialize
terraform init

# Terraform Validate
terraform validate

# Terraform plan
terraform plan

# Terraform Apply
terraform apply -auto-approve

# Terraform Destroy
terraform destroy -auto-approve

Configuration files content

Input Variables

generic-variables.tf

# Input Variables

# AWS Region
variable "aws_region" {
  description = "Region in which AWS Resources to be created"
  type        = string
  default     = "us-east-1"
}

variable "access_key" {
  type        = string
  default     = ""
  description = "AWS Access Key"
  sensitive   = true
}

variable "secret_key" {
  type        = string
  default     = ""
  description = "AWS Secret Key"
  sensitive   = true
}

# Environment Variable
variable "environment" {
  description = "Environment Variable used as a prefix"
  type        = string
  default     = "dev"
}
# Business Division
variable "business_division" {
  description = "Business division name"
  type        = string
  default     = "SpaceX"
}

local-values.tf

• Learn more about Local Values

locals {
  owners = var.business_divsion
  environment = var.environment
  name = "${var.business_divsion}-${var.environment}"
  common_tags = {
    owners = local.owners
    environment = local.environment
  }
}

terraform.tfvars

# Generic Variables
aws_region        = "us-east-1"
access_key        = ""
secret_key        = ""
environment       = "stag"
business_division = "Some Division in the corp."

vpc-variables.tf

# VPC Input Variables

# VPC Name
variable "vpc_name" {
  description = "VPC Name"
  type        = string
  default     = "myvpc"
}

# VPC CIDR Block
variable "vpc_cidr_block" {
  description = "VPC CIDR Block"
  type        = string
  default     = "10.0.0.0/16"
}

# VPC Availability Zones
variable "vpc_availability_zones" {
  description = "VPC Availability Zones"
  type        = list(string)
  default     = ["us-east-1a", "us-east-1b"]
}

# VPC Public Subnets
variable "vpc_public_subnets" {
  description = "VPC Public Subnets"
  type        = list(string)
  default     = ["10.0.101.0/24", "10.0.102.0/24"]
}

# VPC Private Subnets
variable "vpc_private_subnets" {
  description = "VPC Private Subnets"
  type        = list(string)
  default     = ["10.0.1.0/24", "10.0.2.0/24"]
}

# VPC Database Subnets
variable "vpc_database_subnets" {
  description = "VPC Database Subnets"
  type        = list(string)
  default     = ["10.0.151.0/24", "10.0.152.0/24"]
}

# VPC Create Database Subnet Group (True / False)
variable "vpc_create_database_subnet_group" {
  description = "VPC Create Database Subnet Group"
  type        = bool
  default     = true
}

# VPC Create Database Subnet Route Table (True or False)
variable "vpc_create_database_subnet_route_table" {
  description = "VPC Create Database Subnet Route Table"
  type        = bool
  default     = true
}


# VPC Enable NAT Gateway (True or False)
variable "vpc_enable_nat_gateway" {
  description = "Enable NAT Gateways for Private Subnets Outbound Communication"
  type        = bool
  default     = true
}

# VPC Single NAT Gateway (True or False)
variable "vpc_single_nat_gateway" {
  description = "Enable only single NAT Gateway in one Availability Zone to save costs during our demos"
  type        = bool
  default     = true
}

vpc-module.tf

module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "5.1.2"

  # VPC Basic Details
  name            = "${local.name}-${var.vpc_name}"
  cidr            = var.vpc_cidr_block
  azs             = var.vpc_availability_zones
  public_subnets  = var.vpc_public_subnets
  private_subnets = var.vpc_private_subnets

  # Database Subnets
  database_subnets                       = var.vpc_database_subnets
  create_database_subnet_group           = var.vpc_create_database_subnet_group
  create_database_subnet_route_table     = var.vpc_create_database_subnet_route_table
  create_database_internet_gateway_route = true
  create_database_nat_gateway_route      = true

  # NAT Gateways - Outbound Communication
  enable_nat_gateway = var.vpc_enable_nat_gateway
  single_nat_gateway = var.vpc_single_nat_gateway

  # VPC DNS Parameters
  enable_dns_hostnames = true
  enable_dns_support   = true

  tags     = local.common_tags
  vpc_tags = local.common_tags

  # Additional Tags to Subnets
  public_subnet_tags = {
    Type = "Public Subnets"
  }
  private_subnet_tags = {
    Type = "Private Subnets"
  }
  database_subnet_tags = {
    Type = "Private Database Subnets"
  }
}

vpc-outputs.tf

# VPC Output Values

# VPC ID
output "vpc_id" {
  description = "The ID of the VPC"
  value       = module.vpc.vpc_id
}

# VPC CIDR blocks
output "vpc_cidr_block" {
  description = "The CIDR block of the VPC"
  value       = module.vpc.vpc_cidr_block
}

# VPC Private Subnets
output "private_subnets" {
  description = "List of IDs of private subnets"
  value       = module.vpc.private_subnets
}

# VPC Public Subnets
output "public_subnets" {
  description = "List of IDs of public subnets"
  value       = module.vpc.public_subnets
}

# VPC NAT gateway Public IP
output "nat_public_ips" {
  description = "List of public Elastic IPs created for AWS NAT Gateway"
  value       = module.vpc.nat_public_ips
}

# VPC AZs
output "azs" {
  description = "A list of availability zones spefified as argument to this module"
  value       = module.vpc.azs
}

vpc.auto.tfvars

# VPC Variables
vpc_name = "myvpc"
vpc_cidr_block = "10.0.0.0/16"
vpc_availability_zones = ["us-east-1a", "us-east-1b"]
vpc_public_subnets = ["10.0.101.0/24", "10.0.102.0/24"]
vpc_private_subnets = ["10.0.1.0/24", "10.0.2.0/24"]
vpc_database_subnets= ["10.0.151.0/24", "10.0.152.0/24"]
vpc_create_database_subnet_group = true
vpc_create_database_subnet_route_table = true
vpc_enable_nat_gateway = true
vpc_single_nat_gateway = true

Clean-Up

Don't forget to clean up all the created resources to save money on your account !

terraform destroy -auto-approve