Terraform Documentation

What is Terraform?

Terraform is a tool for building, changing, and versioning infrastructure safely and efficiently. Terraform can manage existing and popular service providers as well as custom in-house solutions.

Key Features

• 🏗️ Infrastructure as Code - Define infrastructure using declarative configuration files
• 🔄 Execution Plans - Preview changes before applying them
• 📦 Resource Graph - Build resources in parallel for maximum efficiency
• 🔧 Change Automation - Apply complex changesets with minimal human interaction
• 🌍 Multi-Cloud - Support for AWS, Azure, GCP, and 100+ providers
• 📝 Version Control - Track infrastructure changes in Git

Core Concepts

Installation

Linux

# Install using package manager
# Ubuntu/Debian
sudo apt-get update && sudo apt-get install -y gnupg software-properties-common curl
curl -fsSL https://apt.releases.hashicorp.com/gpg | sudo apt-key add -
sudo apt-add-repository "deb [arch=amd64] https://apt.releases.hashicorp.com $(lsb_release -cs) main"
sudo apt-get update && sudo apt-get install terraform

# Using wget
wget https://releases.hashicorp.com/terraform/1.6.0/terraform_1.6.0_linux_amd64.zip
unzip terraform_1.6.0_linux_amd64.zip
sudo mv terraform /usr/local/bin/

# Verify installation
terraform version

macOS

# Using Homebrew
brew tap hashicorp/tap
brew install hashicorp/tap/terraform

# Or using tfenv (Terraform version manager)
brew install tfenv
tfenv install latest
tfenv use latest

# Verify installation
terraform version

Windows

# Using Chocolatey
choco install terraform

# Or download from: https://www.terraform.io/downloads
# Extract and add to PATH

# Verify installation
terraform version

Quick Start Example

Let's create a simple AWS EC2 instance using Terraform:

1. Create main.tf

# Configure AWS Provider
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

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

# Create EC2 instance
resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"

  tags = {
    Name = "HelloWorld"
  }
}

2. Initialize Terraform

# Initialize Terraform and download providers
terraform init

3. Plan Changes

# Preview changes before applying
terraform plan

4. Apply Changes

# Create the infrastructure
terraform apply

# Type 'yes' to confirm

5. Verify Resources

# List all resources
terraform show

# Get resource state
terraform state list

# View specific resource
terraform state show aws_instance.web

6. Destroy Infrastructure

# Remove all resources
terraform destroy

# Type 'yes' to confirm

Common Terraform Commands

Basic Commands

# Initialize Terraform
terraform init

# Validate configuration
terraform validate

# Format configuration files
terraform fmt

# Show plan
terraform plan

# Apply changes
terraform apply

# Apply without prompt
terraform apply -auto-approve

# Destroy infrastructure
terraform destroy

# Show current state
terraform show

# List resources in state
terraform state list

State Management

# Show specific resource
terraform state show aws_instance.web

# Move resource
terraform state mv aws_instance.old aws_instance.new

# Remove resource from state
terraform state rm aws_instance.web

# Import existing resource
terraform import aws_instance.web i-1234567890abcdef0

Output Commands

# Show outputs
terraform output

# Show specific output
terraform output instance_id

# Show outputs in JSON
terraform output -json

Project Structure

A typical Terraform project structure:

terraform-project/
├── main.tf              # Main configuration
├── variables.tf         # Input variables
├── outputs.tf           # Output values
├── terraform.tfvars     # Variable values
├── terraform.tfstate    # State file (don't commit)
├── terraform.tfstate.backup  # State backup
└── .terraform/          # Provider plugins (don't commit)

Basic Configuration Example

variables.tf

variable "region" {
  description = "AWS region"
  type        = string
  default     = "us-east-1"
}

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

variable "tags" {
  description = "Tags to apply to resources"
  type        = map(string)
  default = {
    Environment = "dev"
    Project     = "example"
  }
}

main.tf

terraform {
  required_version = ">= 1.0"
  
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
  
  backend "s3" {
    bucket = "my-terraform-state"
    key    = "terraform.tfstate"
    region = "us-east-1"
  }
}

provider "aws" {
  region = var.region
}

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

  tags = var.tags
}

outputs.tf

output "instance_id" {
  description = "ID of the EC2 instance"
  value       = aws_instance.web.id
}

output "instance_public_ip" {
  description = "Public IP address of the EC2 instance"
  value       = aws_instance.web.public_ip
}

output "instance_public_dns" {
  description = "Public DNS name of the EC2 instance"
  value       = aws_instance.web.public_dns
}

terraform.tfvars

region        = "us-east-1"
instance_type = "t2.micro"

tags = {
  Environment = "production"
  Project     = "web-app"
  ManagedBy   = "Terraform"
}

Workflow

Why Use Terraform?

Infrastructure as Code Benefits

• ✅ Version Control - Track infrastructure changes in Git
• ✅ Reproducibility - Create identical environments easily
• ✅ Collaboration - Multiple team members can work together
• ✅ Documentation - Code serves as documentation
• ✅ Disaster Recovery - Recreate infrastructure from code
• ✅ Cost Optimization - Easily test and destroy resources

Common Use Cases

• 🏢 Cloud Infrastructure - Provision resources on AWS, Azure, GCP
• 🐳 Container Orchestration - Manage Kubernetes, Docker Swarm
• 🗄️ Database Setup - Configure RDS, Cloud SQL, Azure Database
• 🌐 Networking - Set up VPCs, subnets, load balancers
• 🔐 Security - Configure IAM roles, security groups, policies
• 📊 Monitoring - Set up CloudWatch, Stackdriver, Azure Monitor

Next Steps

Continue learning with our detailed guides:

• Core Concepts - Deep dive into Terraform fundamentals
• Providers & Resources - Working with providers and resources
• State Management - Understanding and managing Terraform state
• Modules - Creating reusable modules
• AWS Setup - Complete AWS setup guide
• GCP Setup - Complete GCP setup guide
• Best Practices - Production-ready practices