Terraform for DevOps — Hands-On Repo

This repository is your one-stop solution for learning Terraform as a DevOps Engineer. It covers basics through advanced features with real AWS infrastructure.

Prerequisites

• Terraform >= 1.5.0 (recommended: 1.14.x)
• AWS CLI configured with valid credentials
• An AWS account (Free Tier works for most examples)

Versions Used

Tool	Version
Terraform	>= 1.5.0
AWS Provider	~> 6.0
EKS Module	~> 21.0
VPC Module	~> 5.0

Repository Structure

terraform-for-devops/
├── terraform.tf          # Provider config & version constraints
├── variables.tf          # Input variables with validation
├── ec2.tf                # EC2 instance, security group, key pair
├── s3.tf                 # S3 bucket with versioning & encryption
├── dynamodb.tf           # DynamoDB table
├── outputs.tf            # Output values
├── script.sh             # EC2 user_data bootstrap script
├── terra-key.pub         # SSH public key
│
├── eks/                  # EKS Cluster (v21.x module)
│   ├── provider.tf       # Provider + locals
│   ├── vpc.tf            # VPC module for EKS networking
│   └── eks.tf            # EKS cluster with managed node groups
│
├── aws_module_project/   # Reusable Modules example
│   ├── terraform.tf      # Provider version constraints
│   ├── providers.tf      # AWS provider region
│   ├── main.tf           # Module composition (dev, stg, prd)
│   └── my_app_infra_module/  # The reusable module
│       ├── variables.tf  # Module inputs with validation
│       ├── my_server.tf  # EC2 instances (count)
│       ├── my_bucket.tf  # S3 bucket
│       ├── my_table.tf   # DynamoDB table
│       └── my_outputs.tf # Module outputs
│
└── examples/             # Modern Terraform feature examples
    ├── for_each.tf       # for_each & dynamic blocks
    ├── validation.tf     # Variable validation blocks
    ├── lifecycle.tf      # lifecycle meta-argument
    ├── moved.tf          # moved blocks (refactoring)
    ├── import.tf         # import blocks (Terraform 1.5+)
    ├── check.tf          # check blocks (continuous assertions)
    ├── removed.tf        # removed blocks (safe removal)
    └── terraform_test/   # Native terraform test (1.6+)

What You'll Learn

Concept	Where to Find It
Provider & version constraints	terraform.tf
Variables with validation	variables.tf, examples/validation.tf
EC2, Security Groups, Key Pairs	ec2.tf
user_data bootstrapping	ec2.tf + script.sh
S3 with versioning & encryption	s3.tf
DynamoDB tables	dynamodb.tf
Outputs	outputs.tf
Reusable modules	aws_module_project/
Multi-environment with modules	aws_module_project/main.tf
EKS cluster (v21.x)	eks/
VPC for Kubernetes	eks/vpc.tf
for_each & dynamic blocks	examples/for_each.tf
Lifecycle rules	examples/lifecycle.tf
Import existing resources	examples/import.tf
Refactoring with moved	examples/moved.tf
Continuous assertions	examples/check.tf
Safe resource removal	examples/removed.tf
terraform test framework	examples/terraform_test/

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Terraform Commands — Complete Guide

1. Setup & Initialization

Install Terraform (Linux/Ubuntu)

wget -O - https://apt.releases.hashicorp.com/gpg | sudo gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list
sudo apt update && sudo apt install terraform

# Verify installation
terraform -v

Install Terraform (macOS)

brew tap hashicorp/tap
brew install hashicorp/tap/terraform

Initialize Terraform

terraform init

• Downloads provider plugins
• Sets up the working directory

2. Core Commands

terraform fmt           # Format code to standard style
terraform validate      # Validate syntax and configuration
terraform plan          # Preview changes without applying
terraform apply         # Create/update infrastructure
terraform apply -auto-approve  # Apply without confirmation
terraform destroy       # Destroy all managed resources
terraform destroy -auto-approve  # Destroy without confirmation

3. Managing State

terraform state list              # List all managed resources
terraform show                    # Show detailed resource info
terraform state mv <src> <dest>   # Move resource in state
terraform state rm <resource>     # Remove from state (not from cloud)

Remote Backend (S3 + DynamoDB for locking)

terraform {
  backend "s3" {
    bucket         = "my-terraform-state"
    key            = "global/s3/terraform.tfstate"
    region         = "us-east-1"
    dynamodb_table = "terraform-lock"
    encrypt        = true
  }
}

4. Variables & Outputs

terraform apply -var="instance_type=t3.small"  # Pass variable via CLI
terraform output                                # Show all outputs
terraform output ec2_public_ip                  # Show specific output

5. Workspaces

terraform workspace new dev       # Create workspace
terraform workspace select prod   # Switch workspace
terraform workspace list          # List all workspaces

6. Testing (Terraform 1.6+)

terraform test                    # Run all .tftest.hcl files

7. Debugging

export TF_LOG=DEBUG               # Enable debug logs
terraform apply 2>&1 | tee debug.log

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Projects

Terraform with Ansible

Get it here

Terraform with GitHub

Get it here

Terraform to EKS

Get it here