Terraform Training Guide for Beginners

1. What is Terraform?

Terraform is an Infrastructure as Code (IaC) tool that allows you to define and provision infrastructure using declarative configuration files. Instead of manually setting up servers, networks, and other resources through cloud provider interfaces, you define your infrastructure in code and let Terraform handle the deployment.

2. Core Concepts

a) Providers

Providers are plugins that allow Terraform to interact with cloud platforms (AWS, Azure, GCP), services (GitHub, DataDog), or other APIs. Example:

provider "aws" {
  region = "us-west-2"
}

b) Resources

Resources are the most important element in Terraform. They describe infrastructure objects like virtual networks, compute instances, or DNS records. Example:

resource "aws_instance" "web_server" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
  
  tags = {
    Name = "Web Server"
  }
}

c) Variables

Variables make your Terraform configurations more flexible and reusable. Example:

variable "environment" {
  description = "Environment (dev/staging/prod)"
  type        = string
  default     = "dev"
}

resource "aws_instance" "web_server" {
  tags = {
    Environment = var.environment
  }
}

3. Basic Workflow

Initialize the Project

terraform init

This downloads required providers and initializes the working directory.

Plan the Changes

terraform plan

This shows what changes Terraform will make to your infrastructure.

Apply Changes

terraform apply

This applies the changes to create/modify your infrastructure.

Destroy Infrastructure

terraform destroy

This removes all resources managed by Terraform.

4. Best Practices

State Management

Store state files remotely (e.g., S3, Azure Storage)
Use state locking to prevent concurrent modifications
Never commit state files to version control

Example backend configuration:

terraform {
  backend "s3" {
    bucket = "terraform-state-bucket"
    key    = "prod/terraform.tfstate"
    region = "us-west-2"
  }
}

Code Organization

Use modules for reusable components
Separate environments using workspaces or directory structure
Follow consistent naming conventions

Example Module Structure

├── modules/
│   ├── vpc/
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   └── outputs.tf
│   └── ec2/
│       ├── main.tf
│       ├── variables.tf
│       └── outputs.tf
├── environments/
│   ├── dev/
│   │   └── main.tf
│   └── prod/
│       └── main.tf
└── terraform.tfvars

5. Hands-on Exercise

Start with a simple example that creates an AWS S3 bucket:

# main.tf
provider "aws" {
  region = "us-west-2"
}

resource "aws_s3_bucket" "demo_bucket" {
  bucket = "my-terraform-demo-bucket"
  
  tags = {
    Environment = "Training"
    Manager     = "Terraform"
  }
}

# Show how to enable versioning
resource "aws_s3_bucket_versioning" "versioning" {
  bucket = aws_s3_bucket.demo_bucket.id
  versioning_configuration {
    status = "Enabled"
  }
}

6. Common Commands Reference

# Initialize working directory
terraform init

# Format code
terraform fmt

# Validate configuration
terraform validate

# Show planned changes
terraform plan

# Apply changes
terraform apply

# Destroy resources
terraform destroy

# Show current state
terraform show

# List resources in state
terraform state list

7. Next Steps

After mastering the basics, explore:

Remote state management
Workspace usage
Complex module creation
CI/CD integration
Import existing infrastructure
Data sources and provisioners

Remember to always refer to the official Terraform documentation for the most up-to-date information and best practices.

amaudy/tf-intro