Digger runs Terraform instead of Opentofu

[peteher]

Problem

Digger continues to use Terraform instead of OpenTofu in specific scenario, even though opentofu: true is explicitly defined.

Setup

• Using Digger vLatest
• no-backend setup
• GitHub actions doing "plan" for branch PR and "apply" upon merge to main
• migrating from Terraform 1.5.7 to Opentofu 1.8.2 where setup worked just fine with Terraform

GHA is as:

      - name: digger apply
        uses: diggerhq/digger@vLatest
        with:
          no-backend: true
          configure-checkout: true
          setup-aws: true
          aws-role-to-assume: "xxx"
          setup-opentofu: true
          opentofu-version: v1.8.2
          upload-plan-destination: aws
          upload-plan-destination-s3-bucket: 'xxx'
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Documentation does not explicitly say but there is a need for the project to state opentofu: true for Digger to start using OpenTofu.

So digger.yaml:

projects:
  - name: default
    workflow: my_custom_workflow
    opentofu: true
workflows:
  my_custom_workflow:
    workflow_configuration:
      on_pull_request_pushed: [ digger plan ]
      on_pull_request_closed: [ digger unlock ]
      on_commit_to_default: [ digger apply ]
auto_merge: false
telemetry: false

After adding opentofu: true to the project:

• manual run is fine - plan and apply works properly, both using OpenTofu
• PR triggered plan is also fine, using OpenTofu

However: PR merge triggered apply keeps using Terraform - and this is the problem.

Excerpt from log:

WARNING: running in 'backendless' mode. No policies will be supported.
GitHub context parsed successfully
Digger digger_config read successfully
Following projects are impacted by pull request #17
- default
GitHub event processed successfully
GitHub event converted to commands successfully
Following commands are going to be executed:
project: default: commands: "digger apply", 
Running 'digger apply' for project 'default' (workflow: my_custom_workflow)
PR status, mergeable: false, merged: true
Pre-apply plan retrieval: stored plan exists in artefact, retrieving
Running command: terraform [init -upgrade=true -input=false -no-color]

See above, running command "terraform" instead of "opentofu".

Workaround

It's not the nicest ever, but in the workflow I can fine-grain the "apply" steps to replace my terraform executable with tofu - so even though Digger keeps using terraform, it really is using tofu:

workflows:
  my_custom_workflow:
    apply:
      steps:
        - run: TF=`which terraform`; rm $TF; ln -s `which tofu` $TF

[motatoes]

@peteher
Thanks for the detailed report, it helped me find the issue pretty quickly. It should be fixed in the next release

[peteher]

@motatoes
Thanks for the quick follow-up and fix! 🎉 Going to test and confirm resolution.

[peteher]

@motatoes
v0.6.42 worked like a charm - thanks again!