Infrastructure as Code: Terraform

Infrastructure as Code enables reproducible infrastructure. This article covers Terraform fundamentals.

Introduction

Infrastructure as Code provides:

Reproducible infrastructure
Version control
Automation
Consistency
Scalability

Terraform Basics

Terraform Configuration

# ✅ Good: Terraform configuration
terraform {
  required_version = ">= 1.0"
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.0"
    }
  }
}

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

# ✅ Good: Create EC2 instance
resource "aws_instance" "app" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"

  tags = {
    Name = "app-server"
  }
}

# ✅ Good: Create security group
resource "aws_security_group" "app" {
  name = "app-sg"

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }
}

# ✅ Good: Output values
output "instance_ip" {
  value = aws_instance.app.public_ip
}

Commands

Terraform Commands

# ✅ Good: Initialize Terraform
terraform init

# ✅ Good: Validate configuration
terraform validate

# ✅ Good: Plan changes
terraform plan

# ✅ Good: Apply changes
terraform apply

# ✅ Good: Destroy infrastructure
terraform destroy

# ✅ Good: Show state
terraform show

# ✅ Good: Format code
terraform fmt

Best Practices

Use variables:

# ✅ Good: Use variables
variable "instance_type" {
  type    = string
  default = "t2.micro"
}

resource "aws_instance" "app" {
  instance_type = var.instance_type
}

# ❌ Bad: Hardcoded values
resource "aws_instance" "app" {
  instance_type = "t2.micro"
}

Use modules:

# ✅ Good: Use modules
module "vpc" {
  source = "./modules/vpc"
  cidr   = "10.0.0.0/16"
}

# ❌ Bad: Inline configuration
resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
}

Use state files:

# ✅ Good: Remote state
terraform {
  backend "s3" {
    bucket = "terraform-state"
    key    = "prod/terraform.tfstate"
    region = "us-east-1"
  }
}

# ❌ Bad: Local state
# Default local state

Summary

Infrastructure as Code is essential. Key takeaways:

Define infrastructure
Use variables
Create modules
Use remote state
Version control
Automate deployment
Manage resources
Follow best practices

Next Steps

Learn about CI/CD
Explore Monitoring
Study Cloud Deployment
Practice Terraform
Automate infrastructure