OpenTofu Migration

Migrate infrastructure-as-code from HashiCorp Terraform to the open-source OpenTofu fork.

When to Use This Skill

Use this skill when:

• Migrating from Terraform to OpenTofu for licensing reasons
• Setting up a new IaC project and evaluating OpenTofu vs Terraform
• Updating CI/CD pipelines to use OpenTofu
• Configuring the OpenTofu provider registry

Prerequisites

• Existing Terraform codebase (0.13+)
• OpenTofu CLI installed
• State backend access (S3, GCS, Azure Blob, etc.)

Install OpenTofu

# 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

Migration Checklist

1. Verify Compatibility

# 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

2. Replace CLI Commands

3. Update Provider Lock File

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

# Verify providers resolve correctly
tofu providers

4. Update State Backend

State files are compatible — no migration needed. Just verify:

# 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

5. Provider Registry

OpenTofu uses its own registry but mirrors most Terraform providers:

# 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-Specific Features

State Encryption (Not in Terraform)

# 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
    }
  }
}

Early Variable/Local Evaluation

# 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
  }
}

CI/CD Pipeline Updates

GitHub Actions

# .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:
          tofu_version: "1.8.0"

      - name: Configure AWS credentials
        uses: aws-actions/configure-aws-credentials@v4
        with:
          role-to-assume: arn:aws:iam::123456789:role/tofu-deploy
          aws-region: us-east-1

      - name: Init
        run: tofu init
        working-directory: infra/

      - name: Plan
        id: plan
        run: tofu plan -no-color -out=tfplan
        working-directory: infra/

      - name: Comment PR with plan

…