Terraform: Infrastructure as Code and Your First Configuration

Step 1: Understand what Terraform does

You write configuration in HashiCorp Configuration Language (HCL) describing the resources you want. Terraform compares that with what exists, shows you a plan of the changes it would make, and applies them when you approve. Provider plugins, such as those for AWS, Azure, Google Cloud, and many others, let it manage each platform. The record of what it manages is kept in a state file.

Step 2: Install Terraform

On macOS use Homebrew with HashiCorp's tap. On Windows, download the zip from HashiCorp's install page, extract terraform.exe, and add its folder to your PATH. On Linux, use HashiCorp's apt or yum repository from the install page. Confirm the installation with the version command. Terraform 1.16 was the current release when this was written; check the install page for the latest.

# macOS
brew tap hashicorp/tap
brew install hashicorp/tap/terraform

terraform version

Step 3: Write your first configuration

Create an empty folder and a file named main.tf. The terraform block declares the providers you need, with version constraints. The configuration creates a random pet name and writes a text file containing it. The ~> constraint allows newer releases within the same major version, which keeps upgrades safe.

terraform {
  required_providers {
    random = {
      source  = "hashicorp/random"
      version = "~> 3.0"
    }
    local = {
      source  = "hashicorp/local"
      version = "~> 2.0"
    }
  }
}

resource "random_pet" "name" {
  length = 2
}

resource "local_file" "greeting" {
  filename = "${path.module}/hello.txt"
  content  = "Hello from ${random_pet.name.id}!\n"
}

output "pet_name" {
  value = random_pet.name.id
}

Step 4: Run the core workflow

init downloads the providers and prepares the folder, and writes a lock file. fmt formats your files and validate checks them. plan previews changes: a plus means create, a minus destroy, a tilde change in place. apply makes them after you confirm. destroy removes everything Terraform created, and you can run it safely here.

terraform init
terraform fmt
terraform validate
terraform plan
terraform apply
terraform output
terraform destroy

Step 5: Know what to commit and the OpenTofu option

Commit your .tf files and the .terraform.lock.hcl lock file, which records the exact provider versions so everyone on the team uses the same ones. Do not commit the .terraform folder, state files, or plan files. Terraform is licensed under the Business Source License, and the community fork OpenTofu, an open-source project hosted by the Linux Foundation, uses the same core workflow with a command called tofu. Check OpenTofu's migration guide before switching an existing project.

# .gitignore
.terraform/
*.tfstate
*.tfstate.*
*.tfplan