opentofu-migration

# macOS
brew install opentofu

# Linux (Debian/Ubuntu)
curl --proto '=https' --tlsv1.2 -fsSL https://get.opentofu.org/install-opentofu.sh \
  -o install-opentofu.sh
chmod +x install-opentofu.sh
./install-opentofu.sh --install-method deb
rm install-opentofu.sh

# Linux (RPM)
./install-opentofu.sh --install-method rpm

# Docker
docker run --rm -v $(pwd):/workspace -w /workspace \
  ghcr.io/opentofu/opentofu:latest init

# Verify installation
tofu --version

# OpenTofu reads Terraform state files directly — no migration needed
# Check your Terraform version (must be <= 1.6.x for full compat)
terraform version

# Run plan with OpenTofu against existing state
tofu init
tofu plan

# Remove Terraform lock and regenerate for OpenTofu
rm .terraform.lock.hcl
tofu init -upgrade

# Verify providers resolve correctly
tofu providers

# backend.tf — works identically with OpenTofu
terraform {
  backend "s3" {
    bucket         = "mycompany-tfstate"
    key            = "prod/infrastructure.tfstate"
    region         = "us-east-1"
    dynamodb_table = "terraform-locks"
    encrypt        = true
  }
}

# Verify state access
tofu init
tofu state list

# versions.tf
terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
    kubernetes = {
      source  = "hashicorp/kubernetes"
      version = "~> 2.25"
    }
    # OpenTofu-specific providers
    random = {
      source  = "hashicorp/random"
      version = "~> 3.6"
    }
  }
}

# OpenTofu supports native state encryption
terraform {
  encryption {
    key_provider "pbkdf2" "my_key" {
      passphrase = var.state_passphrase
    }
    method "aes_gcm" "encrypt" {
      keys = key_provider.pbkdf2.my_key
    }
    state {
      method   = method.aes_gcm.encrypt
      enforced = true
    }
    plan {
      method   = method.aes_gcm.encrypt
      enforced = true
    }
  }
}

# OpenTofu allows variables in backend config and module sources
terraform {
  backend "s3" {
    bucket = var.state_bucket  # Works in OpenTofu, not Terraform
    key    = "${var.project}/terraform.tfstate"
    region = var.aws_region
  }
}

# .github/workflows/tofu.yml
name: OpenTofu
on:
  pull_request:
    paths: ["infra/**"]
  push:
    branches: [main]
    paths: ["infra/**"]

permissions:
  id-token: write
  contents: read
  pull-requests: write

jobs:
  plan:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Setup OpenTofu
        uses: opentofu/setup-opentofu@v1
        with: