OpenTofu : Nice Alternative to Terraform

If you wants to know more about the OpenTofu here are the details

Migrating to OpenTofu from Terraform

OpenTofu 1.6 is compatible with Terraform 1.6. This migration guide will take you through the process of switching from Terraform to OpenTofu.

Step 0: Prepare a disaster recovery plan

Although OpenTofu 1.6 is very similar to Terraform 1.6, it is a non-trivial change affecting your infrastructure. Make sure you have an up to date and tested disaster recovery plan.

Step 1: Apply all changes with Terraform

Before proceeding, make sure that you apply all changes with terraform apply. Running terraform plan should result in no planned changes. While you can switch to OpenTofu with pending changes, it is not recommended.

$ terraform plan

...

No changes. Your infrastructure matches the configuration.

Terraform has compared your real infrastructure against your
configuration and found no differences, so no changes are needed.

Step 2: Install OpenTofu

As a first step, please follow the installation instructions for the OpenTofu CLI tool. Please test if you can successfully execute the tofu command:

$ tofu --version
OpenTofu v1.6.0
on linux_amd64

Step 3: Back up your state file

Before you begin using the tofu binary on your Terraform code, make sure to back up your state file. If you are using a local state file, you can simply make a copy of your terraform.tfstate file in your project directory.

If you are using a remote backend such as an S3 bucket, make sure that you follow the backup procedures for the backend and that you exercise the restore procedure at least once.

Step 4: Initialize OpenTofu

Warning

Should any of the following steps fail, please do not proceed and follow the  rollback instructions below instead. If you suspect the failure may be the result of a bug in OpenTofu,  please help us by opening an issue.

Now you are ready to migrate. Run tofu init in the directory where your Terraform code resides. OpenTofu will download any providers and modules referenced in your configuration from the OpenTofu registry.

Step 5: Inspect the plan

Once initialized, run tofu plan and ensure that there are no pending changes similar to step 1 above. If there are unexpected changes in the plan, roll back to Terraform and troubleshoot your migration. (See the Troubleshooting section below.)

$ tofu plan

...

No changes. Your infrastructure matches the configuration.

OpenTofu has compared your real infrastructure against your
configuration and found no differences, so no changes are needed.

Step 6: Test out a small change

Before you begin using OpenTofu for larger changes, test out tofu apply with a smaller, non-critical change.

Rolling back to Terraform and reporting issues

If you have issues migrating to OpenTofu you can follow these steps to roll back to Terraform:

1. Create another backup of your state file.
2. Run terraform init.
3. Run terraform plan and verify that no unexpected changes are in the plan.
4. Test the rollback with a small, non-critical change.

If you encountered a bug, please report it on GitHub.

Troubleshooting

If you encounter any issues during the migration to OpenTofu, you can join the OpenTofu Slack or ask on  GitHub Discussions.

Error: Failed to query available provider packages

This error happens when a provider you specified in your configuration is not available in the OpenTofu registry. Please roll back to Terraform and make sure your code works with Terraform. If your code works, please  submit an issue to include the provider in the registry.

Error: Module not found

This error happens when a module you specified in your configuration is not available in the OpenTofu registry. Please roll back to Terraform and make sure your code works with Terraform. If your code works, please  submit an issue to include the module in the registry.