tofu-plan-comment

A Forgejo Action that posts tofu plan output on a pull request as one comment, updated in place on every run instead of stacking a new one.

Written for Forgejo Actions. It talks to /repos/{repo}/issues/{n}/comments with curl and jq, which is the same shape GitHub serves, so it also runs on GitHub Actions.

Usage

      - name: Plan
        id: plan
        working-directory: tofu
        run: |
          set +e
          tofu plan -input=false -no-color -lock-timeout=5m > plan-output.txt 2>&1
          rc=$?
          cat plan-output.txt
          exit $rc

      - name: Comment the plan on the PR
        if: always()          # a failed plan belongs on the PR, not only in the log
        uses: ndreno/tofu-plan-comment@v1
        with:
          plan-file: tofu/plan-output.txt
          status: ${{ steps.plan.outcome }}
          token: ${{ github.token }}

if: always() and capturing the plan to a file with set +e are the point: the comment is most useful exactly when the plan fails.

On GitHub, add permissions: pull-requests: write to the job.

Inputs

Input	Required	Default	Meaning
plan-file	yes		File holding the captured plan output
status	yes		Outcome of the plan step, e.g. ${{ steps.plan.outcome }}
token	yes		Token allowed to comment on the pull request
marker	no	tofu-plan	Identifier of the comment to update
title	no	OpenTofu plan	Comment heading
max-body	no	60000	Comment length cap, in characters

Two plans in one repository (say a staging and a production workspace) need two marker values, otherwise they overwrite each other.

What the comment looks like

✅ OpenTofu plan (success)

Plan: 2 to add, 1 to change, 0 to destroy.

Full plan output

…

The summary line is lifted from the plan itself (Plan:, No changes, Apply complete), so it stays whatever OpenTofu decided to say.

A plan longer than max-body keeps its head and tail and loses the middle: the head carries the errors, the tail carries the summary, and the job log still has the whole thing.

Requirements

• curl and jq in the job container.
• A pull_request event. On any other event the action prints a note and exits 0, so it can sit in a workflow that also runs on push.

Development

Canonical repository: github.com/ndreno/tofu-plan-comment, where CI runs. code.forgejo.org/ndreno/tofu-plan-comment mirrors it, so a Forgejo instance whose DEFAULT_ACTIONS_URL points there resolves the bare uses: form. Issues and pull requests go to GitHub.

post-comment.sh is the whole action. The suite stubs curl and asserts on the requests the script makes, so it needs no network and no forge.

bats tests/
shellcheck post-comment.sh tests/stub-curl.sh
yamllint .

Licence

MIT