Infrastructure as Code with Terraform

Stop clicking buttons and start writing code for your infrastructure

· By Yassine
terraform iac devops cloud

Infrastructure as Code with Terraform

Remember the days of manually clicking through cloud consoles to provision resources? Yeah, me neither. Let’s talk about Infrastructure as Code (IaC) and why Terraform is awesome.

Why Infrastructure as Code?

Think of IaC as version control for your infrastructure. Here’s what you get:

  • Reproducibility: Deploy the same thing multiple times
  • Version control: Track changes over time
  • Code review: Catch mistakes before they hit production
  • Documentation: Your code IS your documentation

Terraform Basics

Terraform uses a declarative language called HCL (HashiCorp Configuration Language). Here’s a simple example:

# Configure the AWS Provider
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

# Create a VPC
resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"

  tags = {
    Name = "main-vpc"
    Environment = "production"
  }
}

# Create a subnet
resource "aws_subnet" "public" {
  vpc_id     = aws_vpc.main.id
  cidr_block = "10.0.1.0/24"

  tags = {
    Name = "public-subnet"
  }
}

The Terraform Workflow

  1. Write: Define your infrastructure in .tf files
  2. Plan: Preview changes with terraform plan
  3. Apply: Create/update resources with terraform apply
  4. Destroy: Clean up with terraform destroy (be careful!)
# Initialize Terraform
terraform init

# Preview changes
terraform plan

# Apply changes
terraform apply

# Destroy everything (careful!)
terraform destroy

Best Practices

1. Use Remote State

Never store state files locally. Use remote backends:

terraform {
  backend "s3" {
    bucket = "my-terraform-state"
    key    = "prod/terraform.tfstate"
    region = "us-east-1"

    # Enable state locking
    dynamodb_table = "terraform-locks"
    encrypt        = true
  }
}

2. Use Modules

Don’t repeat yourself. Create reusable modules:

module "vpc" {
  source = "./modules/vpc"

  vpc_cidr = "10.0.0.0/16"
  environment = "production"
  availability_zones = ["us-east-1a", "us-east-1b"]
}

3. Use Variables

Make your code flexible:

variable "instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t3.micro"
}

variable "environment" {
  description = "Environment name"
  type        = string

  validation {
    condition     = contains(["dev", "staging", "prod"], var.environment)
    error_message = "Environment must be dev, staging, or prod"
  }
}

resource "aws_instance" "app" {
  ami           = data.aws_ami.ubuntu.id
  instance_type = var.instance_type

  tags = {
    Environment = var.environment
  }
}

4. Use Outputs

Make important values available:

output "vpc_id" {
  description = "ID of the VPC"
  value       = aws_vpc.main.id
}

output "load_balancer_dns" {
  description = "DNS name of the load balancer"
  value       = aws_lb.main.dns_name
}

Common Gotchas

1. State File Conflicts

Multiple people running Terraform? You’ll get conflicts. Use state locking!

2. Credential Management

Never hardcode credentials:

# ❌ BAD
provider "aws" {
  access_key = "AKIAIOSFODNN7EXAMPLE"
  secret_key = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
}

# ✅ GOOD - Use environment variables or IAM roles
provider "aws" {
  # Credentials from environment or IAM role
  region = var.aws_region
}

3. Blast Radius

Be careful with terraform apply. Use:

  • Workspaces for different environments
  • -target flag to update specific resources
  • Plan files to ensure what you’re applying

Advanced Tips

Use Data Sources

Query existing resources:

data "aws_ami" "ubuntu" {
  most_recent = true
  owners      = ["099720109477"] # Canonical

  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-jammy-22.04-amd64-server-*"]
  }
}

Use Terraform Cloud

For teams, consider Terraform Cloud for:

  • Remote state management
  • Plan/apply automation
  • Policy as code (Sentinel)
  • Private module registry

Conclusion

Terraform turns infrastructure management from a manual chore into a codified, reviewable, and automated process. Start small, use modules, and always run terraform plan before apply.

Your infrastructure will thank you (and so will your teammates).

Happy terraforming! 🌍

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