Provisioning Infrastructure in Multiple Environments with Terraform

In this tutorial, we will cover how to provision infrastructure in multiple environments (such as development, staging, and production) using Terraform. This approach ensures that your infrastructure is consistent across different environments and makes it easier to manage.

Setting Up Directory Structure

To manage multiple environments, we can use a directory structure that separates environment-specific configurations. Create a directory structure like this:

.
├── environments
│   ├── development
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   └── terraform.tfvars
│   ├── staging
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   └── terraform.tfvars
│   └── production
│       ├── main.tf
│       ├── variables.tf
│       └── terraform.tfvars
└── modules
    └── ec2_instance
        ├── main.tf
        ├── variables.tf
        └── outputs.tf

Creating a Reusable Module

Create a reusable module for the infrastructure component you want to manage. In this example, we'll create an EC2 instance module. Add the following files in modules/ec2_instance:

main.tf

resource "aws_instance" "example" {
  ami           = var.ami
  instance_type = var.instance_type
  tags = {
    Name = var.instance_name
  }
}

variables.tf

variable "ami" {
  description = "The AMI to use for the instance"
  type        = string
}

variable "instance_type" {
  description = "The type of instance to use"
  type        = string
}

variable "instance_name" {
  description = "The name of the instance"
  type        = string
}

outputs.tf

output "instance_id" {
  description = "The ID of the EC2 instance"
  value       = aws_instance.example.id
}

output "instance_public_ip" {
  description = "The public IP address of the EC2 instance"
  value       = aws_instance.example.public_ip
}

Configuring Environments

Now, configure each environment to use the module. Update the main.tf file in each environment directory:

main.tf (example for development)

provider "aws" {
  region = var.region
}

module "ec2_instance" {
  source        = "../../modules/ec2_instance"
  ami           = var.ami
  instance_type = var.instance_type
  instance_name = var.instance_name
}

variables.tf (example for development)

variable "region" {
  description = "The AWS region to deploy resources in"
  type        = string
}

variable "ami" {
  description = "The AMI to use for the instance"
  type        = string
}

variable "instance_type" {
  description = "The type of instance to use"
  type        = string
}

variable "instance_name" {
  description = "The name of the instance"
  type        = string
}

terraform.tfvars (example for development)

region         = "us-west-2"
ami            = "ami-0c55b159cbfafe1f0"
instance_type  = "t2.micro"
instance_name  = "dev-instance"

Repeat the configuration for the staging and production environments, updating the terraform.tfvars file with environment-specific values.