devops-basics

1. What is OpenTofu?

https://opentofu.org/docs/intro/

Overview

OpenTofu is an open-source Infrastructure as Code (IaC) tool that is a fork of Terraform, maintained by the Linux Foundation. It was created in response to HashiCorp’s license change from MPL to the Business Source License (BSL) in August 2023.

OpenTofu is:

Drop-in replacement for Terraform: Fully compatible with existing Terraform configurations (HCL syntax, providers, modules, state files)
Open source: Licensed under MPL 2.0, governed by the Linux Foundation
Community-driven: Backed by major companies including AWS, Google, IBM, Red Hat, and many others
Feature-rich: Includes all Terraform features plus new additions like state encryption and enhanced test framework

OpenTofu vs Terraform

Feature	OpenTofu	Terraform
License	MPL 2.0 (open source)	BSL 1.1 (source available)
Governance	Linux Foundation	HashiCorp / IBM
State encryption	✅ Built-in	❌ Not available
Provider compatibility	✅ Same as Terraform	✅ Native
Module registry	registry.opentofu.org	registry.terraform.io
Community	Open contributors	HashiCorp-controlled

Official Documentation

https://opentofu.org/docs/

2. Prerequisites

Basic Linux command-line skills
Understanding of Infrastructure as Code concepts
Cloud provider account (AWS, Azure, or GCP) for cloud examples

3. Installation

Install OpenTofu

Official guide: https://opentofu.org/docs/intro/install/

# macOS
brew install opentofu

# Linux (official installer)
curl --proto '=https' --tlsv1.2 -fsSL https://get.opentofu.org/install-opentofu.sh | sh

# Verify installation
tofu version

Migrate from Terraform

# OpenTofu is CLI-compatible with Terraform
# Simply replace 'terraform' with 'tofu' in your commands
terraform init    →  tofu init
terraform plan    →  tofu plan
terraform apply   →  tofu apply
terraform destroy →  tofu destroy

4. Basics of OpenTofu

OpenTofu Hello World

See: basics/

Core Workflow

# Initialize working directory (downloads providers)
tofu init

# Preview infrastructure changes
tofu plan

# Apply the changes
tofu apply

# Show current state
tofu show

# Destroy all managed infrastructure
tofu destroy

Basic Configuration Example

# main.tf
terraform {
  required_providers {
    local = {
      source  = "hashicorp/local"
      version = "~> 2.4"
    }
  }
}

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

output "file_content" {
  value = local_file.hello.content
}

5. Beyond the Basics

State Encryption (OpenTofu-exclusive feature)

# Encrypt state with a passphrase (OpenTofu only)
terraform {
  encryption {
    key_provider "pbkdf2" "my_passphrase" {
      passphrase = var.state_passphrase
    }
    method "aes_gcm" "my_method" {
      keys = key_provider.pbkdf2.my_passphrase
    }
    state {
      method = method.aes_gcm.my_method
    }
  }
}

Testing with OpenTofu

# tests/basic.tftest.hcl
run "verify_file_created" {
  command = apply

  assert {
    condition     = local_file.hello.content == "Hello from OpenTofu!"
    error_message = "File content does not match expected value"
  }
}

Hands-On Examples

See: practice/

6. More

OpenTofu Cheatsheet

tofu init          # Initialize directory
tofu validate      # Validate configuration
tofu plan          # Show execution plan
tofu apply         # Apply changes
tofu apply -auto-approve  # Apply without confirmation
tofu destroy       # Destroy infrastructure
tofu state list    # List resources in state
tofu state show <resource>  # Show resource details
tofu output        # Show output values
tofu fmt           # Format configuration files

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