Infrastructure as Code (IaC) is a DevOps approach where infrastructure is defined and managed using code instead of manual setup. This makes environments reproducible, version-controlled, and easy to scale.

In this guide, you'll provision an AWS EC2 instance using Terraform.

Requirements

Before starting, install:

• Terraform
• AWS CLI

AWS Credentials Setup

1. Go to IAM → Security credentials in AWS
2. Create access keys
3. Configure locally:

aws configure

This stores credentials in:

• ~/.aws/credentials
• ~/.aws/config

Project Structure

A simple Terraform setup:

.
├── main.tf
├── variables.tf
├── terraform.tfvars
├── outputs.tf

Provider Configuration

Define your cloud provider in main.tf:

provider "aws" {
  profile = "default"
  region  = "eu-north-1"
}

Variables

Define reusable variables in variables.tf:

variable "instance_name" {
  description = "Name tag for EC2 instance"
  type        = string
  default     = "MyNewInstance"
}
variable "ec2_instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t3.micro"
}

Set values in terraform.tfvars:

instance_name      = "MyEC2Name"
ec2_instance_type  = "t3.micro"

EC2 Instance Configuration

Add the resource in main.tf:

resource "aws_instance" "app_server" {
  ami           = "ami-077d1b9f9a1902bbc"
  instance_type = var.ec2_instance_type
  tags = {
    Name = var.instance_name
  }
}

You can find AMI IDs in EC2 → Images → AMI Catalog.

Outputs

Expose useful data in outputs.tf:

output "instance_id" {
  description = "EC2 instance ID"
  value       = aws_instance.app_server.id
}
output "instance_public_ip" {
  description = "Public IP address"
  value       = aws_instance.app_server.public_ip
}

Terraform Workflow

Initialize the project:

• terraform init

Preview changes:

• terraform plan

Apply changes:

• terraform apply

Destroy infrastructure:

• terraform destroy

Important Notes

• State file

Terraform stores infrastructure state in terraform.tfstate.

Do not commit this file to Git.

• Remote state (recommended)

For teams, store state in S3 with locking via DynamoDB.

• Idempotency

Running apply multiple times won’t recreate resources unnecessarily.

• Version control

Treat Terraform code like application code.