Request: Support Compatibility with OpenTofu + `tenv`

[Rishav Dhar]

Is your feature request related to a problem

N/a.

Describe the solution you'd like

With the launch of OpenTofu fork, I'd like to support OpenTofu as a first-class IaC provisioning tool, just like Hashicorp's Terraform.

Describe alternatives you've considered

While we await (pre-)releases to become available, a serviceable workaround has been shared by @zimeg (from Slack) to download, install and initialize OpenTofu CLI in 3 GitHub Actions steps.

- name: Download the tofu source
  uses: actions/checkout@v4
  with:
    repository: opentofu/opentofu
    path: opentofu

- name: Install tofu tooling
  uses: actions/setup-go@v4
  with:
    go-version-file: opentofu/go.mod
    cache-dependency-path: opentofu/go.sum

- name: Prepare the tofu command
  working-directory: opentofu
  run: |
    go build -ldflags "-w -s -X 'github.com/opentofu/opentofu/version.dev=no'" -o bin/tofu .
    echo $(pwd)/bin >> $GITHUB_PATH

Additional context

Issue opentofu/opentofu#556 has been raised in order to deliver a more "drop-in replacement"-able equivalent to hashicorp/setup-terraform.

[Rishav Dhar]

Over the last month, OpenTofu has published opentofu/setup-opentofu to lower the barrier to entry for implementing tofu as part of the CI/CD pipelines.

While we deliver first-class support with OpenTofu, we must ensure backwards-compatibility with Hashicorp Terraform. As result, the decision for choosing between must be easily user-configurable.

[kvendingoldo]

btw. you can also integrate tenv that support Terraform as well as OpenTofu (and Terragrunt :) ) in one tool. It allow you to simplify version management.

[Rishav Dhar]

Good call, @kvendingoldo! Despite using tenv locally, I hadn't considered adding it here before and it's well worth implementing.

Also worth mentioning that, as of the latest v10 release, this Action no longer ships with setup-opentofu or setup-terraform, in order to reduce dependencies and enable the user to supply their own configuration directly.

As a result, I've opened a PR to add a functional demo using tenv in a scenario which tests both terraform and tofu execution simultaneously. Aside, also opened a wee request to allow explicit/unambiguous human-friendly aliases for tenv tool names.

Only remaining issue is PR output comment. More specifically, the aforementioned setup-opentofu/terraform Actions come with their own wrapper script which exposes stdout, stderr, and exitcode automatically by default. These outputs are leveraged when creating PR comments like this. Is there a similar-ish equivalent for sourcing tenv outputs?

[kvendingoldo]

I think that we can easily implement sourcing tenv outputs. Can you open an issue for that, pls? We'll take a look as soon as it would be possible for the team.

[Rishav Dhar]

Sure, @kvendingoldo, I've just gone ahead and opened that request -- though I worry it might be "deceptively simple".

The setup-opentofu/terraform Actions are... Actions. So it's easier for them to supply a wrapper script with custom outputs which are particularly suited for use in CI automation.

I'd be just as happy with workaround suggestions using bash/shell within CI context as well.