release-notes.yaml

name: release-notes

# Generates CHANGELOG.md and a dated docs/news/posts/ blog entry for a tagged
# release, then opens a PR with both. See .github/scripts/generate_release_notes.py for how
# entries are sourced (merged PR titles, parsed for a Conventional Commits prefix) and
# .github/workflows/pr-title-lint.yml for how those titles are kept in that shape.
#
# Cut a release by tagging the branch tip: `git tag v1.1.0 && git push origin v1.1.0` (or via
# `gh release create v1.1.0 --target 1.21.x`). Tag names must match `v*`.

on:
  push:
    tags:
      - 'v*'

permissions:
  contents: write
  pull-requests: write

jobs:
  generate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7
        with:
          fetch-depth: 0

      - uses: actions/setup-python@v7
        with:
          python-version: '3.x'

      - name: Determine the branch this tag was cut from
        id: base
        run: |
          git fetch origin --prune
          # --points-at (not --contains) requires the tag to sit exactly at a branch tip, not
          # just be reachable from one - keeps this deterministic when a tag is reachable from
          # several branches, and enforces the "tag the tip" invariant this workflow assumes.
          BRANCH=$(git branch -r --points-at "${{ github.sha }}" \
            | sed 's/^[* ]*origin\///' \
            | grep -E '^[0-9]+\.[0-9]+\.x$|^main$' \
            | head -n1)
          if [ -z "$BRANCH" ]; then
            echo "::error::Tag ${{ github.ref_name }} isn't at the tip of a recognized release branch (expected an N.N.x or main branch tip)."
            exit 1
          fi
          echo "Releasing from $BRANCH"
          echo "branch=$BRANCH" >> "$GITHUB_OUTPUT"

      - name: Generate changelog and news post
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          python .github/scripts/generate_release_notes.py \
            --repo "${{ github.repository }}" \
            --new-tag "${{ github.ref_name }}" \
            --changelog-path CHANGELOG.md \
            --posts-dir docs/news/posts

      - name: Open pull request
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          if git diff --quiet -- CHANGELOG.md docs/news/posts; then
            echo "Nothing new to record since the previous tag - skipping PR."
            exit 0
          fi

          git config user.name github-actions[bot]
          git config user.email 41898282+github-actions[bot]@users.noreply.github.com

          BRANCH_NAME="release-notes/${{ github.ref_name }}"
          git checkout -b "$BRANCH_NAME"
          git add CHANGELOG.md docs/news/posts
          git commit -m "docs: release notes for ${{ github.ref_name }}"
          git push origin "$BRANCH_NAME"

          gh pr create \
            --base "${{ steps.base.outputs.branch }}" \
            --head "$BRANCH_NAME" \
            --title "docs: release notes for ${{ github.ref_name }}" \
            --body "Auto-generated changelog and news post for [${{ github.ref_name }}](https://github.com/${{ github.repository }}/releases/tag/${{ github.ref_name }})."