sync-fork.yml

name: Sync fork

on:
  workflow_dispatch: {}
  schedule:
    - cron: "15 3 * * *"   # Run every day at 3:15 UTC

jobs:
  sync:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout fork's default branch
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          path: "fork"
          token: ${{ secrets.GH_PAT }}
      - name: Checkout fork's configuration branch
        uses: actions/checkout@v4
        with:
          path: "configuration"
          ref: "renovate-and-workflow-files"
          token: ${{ secrets.GH_PAT }}
      - name: Determine Upstream clone URL
        id: upstream-repo-clone-url
        uses: actions/github-script@v7
        with:
          script: |
            const { data } = await github.rest.repos.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
            });
            if (data.fork) {
              return data.parent.clone_url;
            } else {
              throw new Error('This repository is not a fork.');
            }
          result-encoding: string
      - name: Determine Upstream default branch
        id: upstream-repo-default-branch
        uses: actions/github-script@v7
        with:
          script: |
            const { data } = await github.rest.repos.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
            });
            if (data.fork) {
              return data.parent.default_branch;
            } else {
              throw new Error('This repository is not a fork.');
            }
          result-encoding: string
      - name: Sync fork with upstream
        run: |
          set -ex
          cd fork
          git config --global user.name "github-actions[bot]"
          git config --global user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git remote add upstream ${{ steps.upstream-repo-clone-url.outputs.result }}
          git fetch upstream ${{ steps.upstream-repo-default-branch.outputs.result }}
          UPSTREAM_MOST_RECENT_COMMIT_HASH=$(git log upstream/${{ steps.upstream-repo-default-branch.outputs.result }} -n 1 --format="%H")
          PREVIOUS_SYNC_COMMIT_HASH=$(cat ../configuration/upstream_commit_hash)
          if [ "$PREVIOUS_SYNC_COMMIT_HASH" = "$UPSTREAM_MOST_RECENT_COMMIT_HASH" ]; then
            echo "No need to sync, already up-to-date"
            exit 0
          fi
          
          git reset --hard upstream/${{ steps.upstream-repo-default-branch.outputs.result }}
          # Enforce the usage of our own config (renovate.json5)
          git rm renovate.json* || true
          # Avoid problems where an existing .gitignore file would prevent committing our configuration files
          git rm .gitignore || true
          # Delete existing workflows, we don't need to run them in our fork
          rm -rf .github || true
          # Instead of using "cp -r", rsync allows us to exclude the .git directory
          rsync -av --exclude '.git' ../configuration/ .
          rm upstream_commit_hash
          git add .
          git commit -m "add Renovate and custom workflow files"
          git push --force-with-lease
          
          cd ../configuration
          # git config user.name "github-actions[bot]"
          # git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          echo $UPSTREAM_MOST_RECENT_COMMIT_HASH > upstream_commit_hash
          git add upstream_commit_hash
          git commit -m "update commit hash to $UPSTREAM_MOST_RECENT_COMMIT_HASH"
          git push