Terraform

TL;DR

What: An infrastructure as code tool for provisioning cloud resources.

Why: Declarative syntax, multi-cloud, state management, reproducible infrastructure.

Quick Start

Install:

brew install terraform  # macOS
# or download from terraform.io

Create main.tf:

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

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

resource "aws_instance" "example" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"

  tags = {
    Name = "example-instance"
  }
}

Run:

terraform init
terraform plan
terraform apply

Cheatsheet

Command	Description
terraform init	Initialize working directory
terraform plan	Preview changes
terraform apply	Apply changes
terraform destroy	Destroy infrastructure
terraform fmt	Format code
terraform validate	Validate configuration
terraform output	Show outputs
terraform state list	List resources in state

Gotchas

Variables

# variables.tf
variable "instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t2.micro"
}

# main.tf
resource "aws_instance" "example" {
  instance_type = var.instance_type
}

# terraform.tfvars
instance_type = "t3.small"

Outputs

output "instance_ip" {
  value       = aws_instance.example.public_ip
  description = "Public IP of the instance"
}

Data sources

data "aws_ami" "ubuntu" {
  most_recent = true
  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"]
  }
  owners = ["099720109477"]
}

resource "aws_instance" "example" {
  ami = data.aws_ami.ubuntu.id
}

Modules

module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "5.0.0"

  name = "my-vpc"
  cidr = "10.0.0.0/16"
}

Next Steps

• Terraform Documentation - Official docs
• Terraform Registry - Providers and modules
• Terraform Tutorials - Learn
• Terraform Best Practices - Guidelines