Terraform & OpenTofu - Infrastructure as Code¶

Introduction to Terraform¶

Terraform is an Infrastructure as Code (IaC) tool developed by HashiCorp that allows defining and managing infrastructure declaratively using configuration files.

Introduction to OpenTofu¶

OpenTofu is a fork of Terraform that emerged in 2023 as a response to HashiCorp's license change from MPL 2.0 to BSL 1.1. OpenTofu maintains full compatibility with Terraform while ensuring it remains open-source software under the MPL 2.0 license.

Comparison: Terraform vs OpenTofu¶

Compatibility¶

Terraform: Original HashiCorp version
OpenTofu: 100% compatible with Terraform, including:
Identical HCL syntax
Same providers and modules
Same commands and workflows
Transparent migration

Licenses¶

Terraform: BSL 1.1 (Business Source License) - restrictive for commercial use
OpenTofu: MPL 2.0 (Mozilla Public License) - truly open source

Development¶

Terraform: Developed by HashiCorp
OpenTofu: Community-developed, led by Gruntwork and other contributors

Roadmap¶

Terraform: Controlled by HashiCorp
OpenTofu: Open roadmap driven by the community

Migration¶

Migration from Terraform to OpenTofu is completely transparent:

# Simply replace the binary
# .tf, .tfvars, and .tfstate files work without changes

Fundamental concepts¶

Providers¶

Providers are plugins that allow Terraform to interact with different services and platforms.

# AWS provider configuration
provider "aws" {
  region = "us-west-2"
}

Resources¶

Resources represent infrastructure objects that Terraform manages.

# Create an EC2 instance
resource "aws_instance" "example" {
  ami           = "ami-12345678"
  instance_type = "t2.micro"

  tags = {
    Name = "ExampleInstance"
  }
}

Data Sources¶

Data sources allow obtaining information about existing resources.

# Get AMI information
data "aws_ami" "ubuntu" {
  most_recent = true

  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"]
  }
}

Basic syntax¶

Variables¶

# variables.tf
variable "instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t2.micro"
}

variable "environment" {
  description = "Deployment environment"
  type        = string
}

Outputs¶

# outputs.tf
output "instance_id" {
  description = "ID of created instance"
  value       = aws_instance.example.id
}

output "public_ip" {
  description = "Public IP of instance"
  value       = aws_instance.example.public_ip
}

Basic commands¶

# Initialize Terraform
terraform init

# Plan changes
terraform plan

# Apply changes
terraform apply

# Destroy infrastructure
terraform destroy

# Show state
terraform show

# List resources
terraform state list

Use cases¶

Cloud infrastructure management
Deployment automation
Configuration management
Multi-cloud deployments

Best practices¶

Use code versioning
Separate configuration by environments
Use reusable modules
Implement security policies
Document configurations

Next steps¶

In the following sections we will explore: - Terraform modules - Workspaces and remote states - CI/CD integration - Policies with Sentinel - Terraform Cloud

Additional resources¶