trigger-template-update.yml

name: Update Child Repository Template

on:
  release:
    types: [published, released]
  push:
    tags:
      - "v*"
  workflow_dispatch:
    inputs:
      target_repository:
        description: "Target repository to update (default: mjun0812/python-project-template)"
        required: false
        default: "mjun0812/python-project-template"

jobs:
  update-child-template:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout child repository
        uses: actions/checkout@v7
        with:
          repository: ${{ github.event.inputs.target_repository || 'mjun0812/python-project-template' }}
          token: ${{ secrets.CHILD_REPO_TOKEN }}
          path: child-repo

      - name: Install uv
        uses: astral-sh/setup-uv@v10.3.0

      - name: Resolve template version
        id: version
        env:
          # The Release workflow creates the release with GITHUB_TOKEN, and
          # GitHub does not start workflow runs from events raised by that
          # token, so the release trigger only fires for a release published by
          # hand. A tag push has no release context and must name itself.
          RELEASE_TAG: ${{ github.event.release.tag_name }}
          REF_TYPE: ${{ github.ref_type }}
          REF_NAME: ${{ github.ref_name }}
          RUN_NUMBER: ${{ github.run_number }}
          SERVER_URL: ${{ github.server_url }}
          REPOSITORY: ${{ github.repository }}
        run: |
          if [ -n "${RELEASE_TAG}" ]; then
            version="${RELEASE_TAG}"
          elif [ "${REF_TYPE}" = "tag" ]; then
            version="${REF_NAME}"
          else
            version="latest"
          fi
          echo "value=${version}" >> "$GITHUB_OUTPUT"
          # A manual run has no version to name its branch after, so fall back
          # to the run number to keep branches from colliding, and link no
          # release notes because there is no release to point at.
          if [ "${version}" = "latest" ]; then
            echo "slug=${RUN_NUMBER}" >> "$GITHUB_OUTPUT"
          else
            echo "slug=${version}" >> "$GITHUB_OUTPUT"
            echo "release_url=${SERVER_URL}/${REPOSITORY}/releases/tag/${version}" >> "$GITHUB_OUTPUT"
          fi

      - name: Update template in child repository
        id: update
        working-directory: child-repo
        run: |
          # Update from template. --defaults answers prompts added since the
          # child repository was last updated; without it Copier would try to
          # ask interactively and fail.
          uvx copier update -A --defaults --trust

          # Copier writes conflicting files with inline markers and leaves them
          # unmerged in the index, which stops the pull request action from
          # creating its branch. Stage them so the pull request is still opened,
          # and describe them so the markers are resolved before it is merged.
          conflicts="$(git diff --name-only --diff-filter=U)"
          if [ -n "${conflicts}" ]; then
            echo "conflicts=true" >> "$GITHUB_OUTPUT"
            {
              echo "conflict_note<<CONFLICT_NOTE_EOF"
              echo "### Conflicts to resolve"
              echo
              echo "Copier could not merge these files. They are committed with conflict markers"
              echo '(`<<<<<<<`, `=======`, `>>>>>>>`); resolve every marker before merging.'
              echo
              echo "${conflicts}" | sed 's/^/- `/; s/$/`/'
              echo "CONFLICT_NOTE_EOF"
            } >> "$GITHUB_OUTPUT"
            echo "${conflicts}" | sed 's/^/::warning::Conflict left for manual resolution in /'
            git add -A
          else
            echo "conflicts=false" >> "$GITHUB_OUTPUT"
          fi

      - name: Check for changes
        id: changes
        working-directory: child-repo
        run: |
          # git diff alone would miss an update that only adds files, because
          # those stay untracked until the pull request action commits them.
          if [ -z "$(git status --porcelain)" ]; then
            echo "has_changes=false" >> $GITHUB_OUTPUT
          else
            echo "has_changes=true" >> $GITHUB_OUTPUT
          fi

      - name: Create Pull Request
        if: steps.changes.outputs.has_changes == 'true'
        uses: peter-evans/create-pull-request@v8
        with:
          token: ${{ secrets.CHILD_REPO_TOKEN }}
          path: child-repo
          commit-message: |
            Update template to version ${{ steps.version.outputs.value }}
          title: "Update template to version ${{ steps.version.outputs.value }}${{ steps.update.outputs.conflicts == 'true' && ' (resolve conflicts)' || '' }}"
          body: |
            ## Template Update

            This PR updates the project template to version `${{ steps.version.outputs.value }}`.

            ### Changes
            - Updated from template: ${{ github.repository }}
            - Template version: ${{ steps.version.outputs.value }}
            ${{ steps.version.outputs.release_url && format('- Release notes: {0}', steps.version.outputs.release_url) || '' }}

            ${{ steps.update.outputs.conflict_note }}

            ### Testing
            Please review the changes and test the updated template before merging.

            ---
            *This PR was automatically created by the template update workflow.*
          branch: template-update-${{ steps.version.outputs.slug }}
          delete-branch: true