Terraform Guide

What is Terraform?

Terraform is an Infrastructure as Code (IaC) tool made by HashiCorp. Instead of clicking around in a cloud dashboard to create servers, databases, and networks, you write simple configuration files that describe what you want. Terraform then figures out how to make it happen.

Think of it like a recipe: you write down the ingredients and steps (your .tf files), and Terraform is the chef that follows the recipe to build your infrastructure. Change the recipe? Terraform updates only what changed. Delete the recipe? Terraform tears everything down.

If you have Homebrew installed (and you should!), installing Terraform takes one command:

Verify the install:

We'll build this in three small moves: make a project folder, create an empty config file, then paste your first Terraform code into it. We'll use the local_file resource — it creates a file on your own computer, so no cloud account needed.

1. Create a project folder. mkdir makes the directory and cd moves you into it so every command you run after this happens inside the project.

2. Create an empty main.tf file. Terraform reads every .tf file in the current folder, and main.tf is the conventional name for the primary config. touch creates the file if it doesn't exist yet.

3. Open main.tf in your editor and paste the code below. Use the Copy button on the top right of the block, then paste the whole thing into the empty file and save. Don't worry about the syntax yet — we'll unpack it right after.

terraform {
  required_providers {
    local = {
      source  = "hashicorp/local"
      version = "~> 2.0"
    }
  }
}

resource "local_file" "hello" {
  content  = "Hello, Terraform!"
  filename = "${path.module}/hello.txt"
}

Every Terraform project follows this cycle. Let's walk through each step.

Step 1: terraform init

Initialize the project. Downloads the provider plugins you declared.

Step 2: terraform plan

Preview what Terraform will do — without actually doing it.

Step 3: terraform apply

Execute the plan. Terraform will ask you to confirm with yes.

Step 4: terraform destroy

Tear down everything Terraform created. It will ask for confirmation.

After running terraform apply, Terraform creates a file called terraform.tfstate. This is Terraform's memory — it tracks what resources exist and their current configuration.

Key things about state:

• State maps your config to real-world resources
• Without state, Terraform wouldn't know what it already created
• State files can contain sensitive data — never commit them to Git
• For teams, use remote state (S3, Terraform Cloud, etc.)

*.tfstate
*.tfstate.*
.terraform/
.terraform.lock.hcl

What Are Providers?

A provider is a Terraform plugin that knows how to talk to a specific API. Want to create an AWS EC2 instance? You need the AWS provider. Want to manage a GitHub repo? You need the GitHub provider. Each provider adds resource types and data sources you can use in your config.

Providers are declared in your terraform { required_providers { } } block and downloaded automatically when you run terraform init. Most are maintained by HashiCorp or the service vendor and are published to the Terraform Registry.