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Željko Šević
Željko Šević

Posted on Edited on Originally published at sevic.dev

Infrastructure as Code (IaC) with Terraform (AWS EC2 Example)

#terraform #aws #devops #infrastructure

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
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This stores credentials in:

  • ~/.aws/credentials
  • ~/.aws/config

Project Structure

A simple Terraform setup:

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

Define your cloud provider in main.tf:

provider "aws" {
  profile = "default"
  region  = "eu-north-1"
}
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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"
}
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Set values in terraform.tfvars:

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

  • Idempotency

Running apply multiple times won’t recreate resources unnecessarily.

  • Version control

Treat Terraform code like application code.

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