feat(): enable auto-merge on bump PRs

[Gudsfile]

Follows up on #25.

Once the build matrix passes on a bump PR, auto-merge triggers automatically, no need to merge manually.

How it works

After peter-evans/create-pull-request opens a new bump/duckdb-X.Y.Z PR, the workflow calls gh pr merge --auto --merge on it. The merge happens only when all required status checks pass. If any job fails (e.g. a Python version no longer supported by DuckDB), the PR stays open for review.

Setup required

In addition to the setup described in #25:

1. Settings > General > enable Allow auto-merge
2. Branch protection on main: configure Build DuckDB (the package-duckdb matrix jobs) as required status checks

Open question

Auto-merge is intentionally gated on the build matrix only. However, until PYTHON_VERSIONS is managed automatically (detecting which Python versions DuckDB ships wheels for and which Lambda supports), a passing build does not guarantee complete coverage, it only validates the versions currently in the matrix.

My approach would be to: keep "Require approvals" enabled on main so a reviewer can check PYTHON_VERSIONS before merging. Auto-merge would still remove the need to click merge manually, but would wait for the approval first. Or check Python versions in the CI #29.

[bengeois]

Thanks for this PR, really helpful!

I was going through the configuration and ran into an issue with the required status checks: the matrix jobs each generate a separate check (Build DuckDB (3.10, x86_64), Build DuckDB (3.11, arm64), etc.), so you'd have to add every combination individually in the branch protection rule, and update it each time PYTHON_VERSIONS changes.

The standard fix is to add a small summary job that depends on the whole matrix and acts as a single gate:

all-builds-passed:
  name: All builds passed
  needs: [package-duckdb]
  if: always()
  runs-on: ubuntu-latest
  steps:
    - name: Check matrix result
      run: |
        if [ "${{ needs.package-duckdb.result }}" != "success" ]; then
          exit 1
        fi

I would then only need to configure All builds passed as the required status check, one stable entry, regardless of how many matrix combinations exist.

What do you think ? Can you include this in your PR if you agree ?

[Gudsfile]

What do you think ? Can you include this in your PR if you agree ?

Good point, it’s been added!

[Gudsfile]

Hi @bengeois, since #29 has been merged you could now add check-python-versions to the required status check and maybe remove the approval requirements.

[bengeois]

Setup completed ✅

Thanks @Gudsfile 🙌