Terraform Tutorial

A practical tour of Terraform using AWS, from your first apply to running it in production with CI/CD, policy checks, and a team.

Who This Is For

• Engineers who've clicked through the AWS console and want to stop
• Developers who know what infrastructure is but have never written it as code
• Teams tired of "works in Sarah's environment, broken in Tom's"
• Anyone who has seen a rogue apply nuke a production resource and wants to prevent the next one

Contents

Fundamentals

1. Introduction: What Terraform is, install, providers, first apply
2. HCL Basics: Blocks, arguments, expressions, references
3. Variables and Outputs: Input variables, outputs, locals, types, .tfvars

Core Concepts

4. Resources and Data Sources: Lifecycle, depends_on, count, for_each
5. State: What state is, where it lives, terraform state commands
6. Modules: Writing and consuming modules, registry, versioning

Advanced

7. Remote Backends: S3 backend, DynamoDB locking, workspaces
8. Environments: Dev, staging, production patterns

Ecosystem

9. CI/CD: GitHub Actions plan/apply, drift detection, PR workflows
10. Testing and Validation: validate, fmt, tflint, Terratest, policy-as-code
11. Ecosystem: Terragrunt, Atlantis, Spacelift, OpenTofu, Terramate

Mastery

12. Best Practices: Directory structure, naming, production patterns, anti-patterns

How to Use This Tutorial

1. Read sequentially for a complete path from zero to production-ready
2. Have an AWS account open. A free-tier account is enough for every example
3. Destroy what you create. Each chapter ends with terraform destroy; don't leave resources running

Quick Reference

Essential Commands

# The core loop
terraform init          # download providers, initialize backend
terraform plan          # preview changes (read-only)
terraform apply         # apply changes (with confirmation)
terraform destroy       # tear down managed resources

# Code quality
terraform fmt           # auto-format .tf files
terraform validate      # check syntax and internal consistency

# State operations
terraform state list                 # show tracked resources
terraform state show <addr>          # show one resource
terraform state mv <src> <dst>       # rename or move a resource
terraform state rm <addr>            # untrack (without destroying)

# Workspace
terraform workspace list
terraform workspace new staging
terraform workspace select production

Hello World (Your First Bucket)

terraform {
  required_version = ">= 1.6"

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

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

resource "aws_s3_bucket" "notes" {
  bucket = "ada-notes-2026-04-19"
}

Run:

terraform init
terraform plan
terraform apply
terraform destroy

Common Patterns

# Input variable with a default
variable "environment" {
  type    = string
  default = "dev"
}

# Output
output "bucket_name" {
  value = aws_s3_bucket.notes.bucket
}

# Local (computed once)
locals {
  common_tags = {
    Environment = var.environment
    ManagedBy   = "terraform"
  }
}

# Data source (read existing resources)
data "aws_caller_identity" "current" {}

# count (identical copies)
resource "aws_s3_bucket" "logs" {
  count  = 3
  bucket = "logs-${count.index}"
}

# for_each (per-key uniqueness)
resource "aws_s3_bucket" "per_env" {
  for_each = toset(["dev", "staging", "prod"])
  bucket   = "notes-${each.key}"
}

# Module call
module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "5.5.0"

  name = "main"
  cidr = "10.0.0.0/16"
}

Learning Path Suggestions

Stop clicking in the AWS console (roughly 6 hours)

1. Chapters 01 to 04 to write and apply real Terraform
2. Chapter 05 for state, so you don't panic the first time it surprises you
3. Chapter 12 for production habits before you ship

Team-ready Terraform (roughly 12 hours)

1. All chapters in order
2. Build a small real project (a VPC + a few services) as you go
3. Set up CI/CD from chapter 9 on a personal repo

Evaluating tools around Terraform (roughly 3 hours)

1. Chapter 11 for the ecosystem
2. Chapter 10 for testing and policy
3. Chapter 08 for environment patterns

Additional Resources

• Terraform docs: the canonical reference
• AWS provider docs: every resource and argument
• Terraform Best Practices by Anton Babenko: practical patterns
• OpenTofu: the open-source fork of Terraform, drop-in compatible
• Terragrunt docs: the wrapper that solves some of Terraform's ergonomic gaps
• awesome-terraform: a curated list

Terraform Version

This tutorial is written for Terraform 1.6+ (and works unchanged on OpenTofu 1.6+). AWS provider version ~> 5.0. Older versions work with small tweaks; some newer features require the versions listed.