Terraform for Beginners

Infrastructure as Code

Define infrastructure in files. Review, version, repeat.

Basic Structure

# main.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

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

resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t3.micro"

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

Common Commands

# Initialize (download providers)
terraform init

# Preview changes
terraform plan

# Apply changes
terraform apply

# Destroy resources
terraform destroy

Variables

# variables.tf
variable "environment" {
  description = "Environment name"
  type        = string
  default     = "dev"
}

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

# Use them
resource "aws_instance" "web" {
  instance_type = var.instance_type
  tags = {
    Environment = var.environment
  }
}

Outputs

output "instance_ip" {
  value = aws_instance.web.public_ip
}

Remote State

Don't commit state files:

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

Modules

Reusable components:

module "vpc" {
  source = "./modules/vpc"
  cidr   = "10.0.0.0/16"
}

module "web" {
  source    = "./modules/ec2"
  vpc_id    = module.vpc.id
  subnet_id = module.vpc.public_subnet_id
}

Tips

1. Always run plan before apply
2. Use workspaces for environments
3. Keep modules small and focused
4. Lock provider versions