Terraform

Lesson 4

Welcome to Infrastructure as Code! Terraform lets you define your cloud infrastructure using simple configuration files. Instead of clicking through the AWS console to create resources, you’ll write code that describes what you want—then Terraform makes it happen. This approach is faster, repeatable, and version-controlled, making it the industry standard for managing cloud resources.

Terraform

What is Terraform?

Terraform is like a blueprint system for cloud infrastructure. You describe what you want (servers, databases, networks) in configuration files, and Terraform figures out how to create it. Here’s why it’s essential:

Reproducible: Deploy the same infrastructure in dev, staging, and production
Version Controlled: Track changes to your infrastructure just like application code
Collaborative: Team members can review and approve infrastructure changes
Cloud Agnostic: Works with AWS, Azure, Google Cloud, and more

Installing Terraform

Let’s get Terraform installed on your system. Choose your operating system below:

macOS Installation

The easiest way is using Homebrew:

# Install Homebrew if you don't have it
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

# Add HashiCorp tap
brew tap hashicorp/tap

# Install Terraform
brew install hashicorp/tap/terraform

# Verify installation
terraform --version

Linux Installation (Ubuntu/Debian)

# Add HashiCorp GPG key
wget -O- https://apt.releases.hashicorp.com/gpg | gpg --dearmor | sudo tee /usr/share/keyrings/hashicorp-archive-keyring.gpg

# Add HashiCorp repository
echo "deb [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

# Update and install
sudo apt update && sudo apt install terraform

# Verify installation
terraform --version

Windows Installation

Download Terraform from terraform.io/downloads
Unzip the file to a directory (e.g., C:\terraform)
Add the directory to your PATH:
- Search “Environment Variables” in Start Menu
- Edit System Environment Variables
- Add C:\terraform to Path
Open a new Command Prompt and verify: terraform --version

Your First Terraform Project

Time to create your first cloud resource! We’ll deploy an EC2 instance (a virtual server) in AWS.

Step 1: Create Your Project Directory

# Create and enter project directory
mkdir my-first-terraform
cd my-first-terraform

Step 2: Write Your First Terraform Configuration

Create a file called main.tf in your code editor:

# Configure the AWS Provider
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
  required_version = ">= 1.0"
}

# Set up the AWS provider
provider "aws" {
  region  = "us-east-1"
  profile = "learn-aws"  # Use the profile we created earlier
}

# Create an EC2 instance
resource "aws_instance" "my_first_server" {
  ami           = "ami-0c02fb55956c7d316"  # Amazon Linux 2 AMI
  instance_type = "t2.micro"                # Free tier eligible

  tags = {
    Name = "My-First-Terraform-Server"
    Environment = "Learning"
  }
}

Understanding the Code

Let’s break down what each section does:

1. Terraform Block

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

This tells Terraform which providers (cloud platforms) you’re using. The ~> 5.0 means “use version 5.x but not 6.0”.

2. Provider Block

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

Configures how to connect to AWS. The profile refers to the credentials we set up earlier.

3. Resource Block

resource "aws_instance" "my_first_server" {
  ami           = "ami-0c02fb55956c7d316"
  instance_type = "t2.micro"
  
  tags = {
    Name = "My-First-Terraform-Server"
  }
}

Defines what to create:

aws_instance: The type of resource (EC2 instance)
my_first_server: Your name for this resource in Terraform
ami: The operating system image
instance_type: The size of the server (t2.micro is free tier)
tags: Labels to help you identify resources in AWS

Step 3: Initialize Terraform

Before Terraform can work, it needs to download the AWS provider plugin:

terraform init

You’ll see output like:

Initializing the backend...
Initializing provider plugins...
- Installing hashicorp/aws v5.x.x...
- Installed hashicorp/aws v5.x.x

Terraform has been successfully initialized!

Step 4: Preview Your Changes

Before creating anything, let’s see what Terraform will do:

terraform plan

This shows:

Resources to be created (marked with +)
Resource properties
No actual changes are made yet

Step 5: Create Your Infrastructure!

Ready? Let’s create your server:

terraform apply

Terraform will:

Show you the plan again
Ask for confirmation (type yes)
Create your EC2 instance
Display a success message

Step 6: See Your Server in AWS

Log into the AWS Console
Navigate to EC2 (search in the top bar)
Click “Instances” in the left sidebar
You should see your instance named “My-First-Terraform-Server”!

first-instance

Important Terraform Commands

Here are the commands you’ll use most:

Command	What it does
`terraform init`	Initialize a project, download providers
`terraform plan`	Preview changes without applying them
`terraform apply`	Create or update infrastructure
`terraform destroy`	Remove all resources (use carefully!)
`terraform fmt`	Format your code properly
`terraform validate`	Check if your configuration is valid

Clean Up Your Resources

AWS charges for running instances, so let’s clean up:

terraform destroy

Type yes when prompted. This removes all resources defined in your Terraform files.

Best Practices from Day One

Start with these good habits:

Always run plan before apply: Review changes before making them
Use meaningful names: web_server is better than instance1
Add tags: Help identify resources and track costs
Format your code: Run terraform fmt before committing
Don’t hardcode secrets: Never put passwords or keys in .tf files

Common Beginner Issues

“No valid credential sources found”

Check your AWS profile: aws configure list --profile learn-aws
Ensure you’re using the correct profile name in your provider block

“Instance type not supported in this availability zone”

Some instance types aren’t available everywhere
Try changing the region or instance type

“Cannot destroy resource - does not exist”

Your resources might have been deleted outside Terraform
Run terraform refresh to sync state

Practice Exercise

Try modifying your configuration:

Change the instance type to t3.micro
Add more tags (like Owner = "Your Name")
Run terraform plan to see the changes
Apply the changes with terraform apply

Click for solution

```hcl resource "aws_instance" "my_first_server" { ami = "ami-0c02fb55956c7d316" instance_type = "t3.micro" # Changed from t2.micro tags = { Name = "My-First-Terraform-Server" Environment = "Learning" Owner = "Your Name" # Added new tag } } ```

What You’ve Accomplished

✅ Installed Terraform on your system
✅ Wrote your first Infrastructure as Code
✅ Created real cloud infrastructure with code
✅ Learned essential Terraform commands
✅ Safely destroyed resources to avoid charges

You’ve just taken a huge step! Instead of clicking through the AWS console, you defined infrastructure as code. This is how professionals manage thousands of servers across multiple environments.

Next Steps

Ready to dive deeper into AWS? Head to the EC2 section where you’ll learn to build more complex infrastructure, including web servers you can actually connect to!

Remember: You can practice this lesson as many times as needed. Just run terraform destroy to clean up, and start fresh. The more you practice, the more natural it becomes!