Terraform: Infrastructure as Code

What is Terraform?

Terraform is an open-source infrastructure as code (IaC) tool created by HashiCorp. It allows you to define and provision infrastructure using a declarative configuration language called HCL (HashiCorp Configuration Language). Terraform can manage infrastructure across multiple cloud providers and services.

Unlike imperative approaches where you specify step-by-step instructions, Terraform uses a declarative approach where you describe the desired end state, and Terraform figures out how to achieve it while tracking the actual state of your infrastructure.

Terraform Project Calculator

Terraform Core Workflow

resource "aws_instance" "web" {
  ami = "ami-12345"
  instance_type = "t3.micro"
}

$ terraform show
# aws_instance.web:
resource "aws_instance" "web" {
  id = "i-1234567890abcdef0"
}

Terraform Configuration Patterns

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

provider "aws" {
  region = var.aws_region
}

module "vpc" {
  source = "terraform-aws-modules/vpc/aws"
  version = "3.0.0"

  name = "my-vpc"
  cidr = "10.0.0.0/16"
  azs = ["us-west-2a", "us-west-2b"]
  public_subnets = ["10.0.1.0/24", "10.0.2.0/24"]
}

terraform {
  backend "s3" {
    bucket = "my-terraform-state"
    key = "prod/terraform.tfstate"
    region = "us-west-2"
    dynamodb_table = "terraform-locks"
    encrypt = true
  }
}

Real-World Terraform Implementations

Terraform Best Practices