action-mirror-commit-status

This action mirrors a status check from one name to another on a single commit.

Description

Why on earth would you need to mirror a status check? This is to work around a missing feature in Actions combined with missing merge queue support in some CI systems (Drone in our case).

This is the scenario:

• You have a CI system that doesn't support merge queues (like Drone).
• You have a required status check continuous-integration/drone/pr that must
  pass before anything can be pushed to the main branch.
• You'd like to enable GitHub merge queues.

The problem that happens is this:

• A PR passes its checks and the developer presses the "Merge" button to merge
  the PR via the merge queue.
• GitHub creates a temporary branch gh-readonly-queue/<target branch>/... and
  pushes your commit on top of the target branch.
• A push webhook is sent to the CI system, which starts a new build.
• The CI system runs it as it's configured to.
• In Drone's case, a status check continuous-integration/drone/push is created
  on the commit in the temporary branch, and set to "pending", then eventually
  "success", "failure" or "error".
• This check has a different name: it ends with push instead of pr.
• The merge queue is stuck.

This action is a workaround for that scenario. There is an event sent when status checks are updated. This action listens for that event and mirrors the status from one check to another.

Usage

In the above scenario, you would configure this action to run on the status event, when the branch starts withgh-readonly-queue/* like so:

on:
  status:

run-name:
  Mirror status ${{ github.event.context }} for ${{ github.ref }} (${{
  github.event_name }})

jobs:
  commit-status:
    if:
      github.event.context == 'continuous-integration/drone/push' &&
      startsWith(github.event.branches[0].name, 'gh-readonly-queue/main/')

    permissions:
      statuses: write

    runs-on: ubuntu-latest
    steps:
      - name: Mirror commit status
        uses: grafana/action-mirror-commit-status@sha123456
        with:
          to-status: continuous-integration/drone/pr

Note that this workflow needs to be present on the target branch (main in this case).