propagate.yml

name: propagate

on:
  push:
    branches: [main]

permissions:
  contents: write
  pull-requests: write

jobs:
  propagate:
    strategy:
      fail-fast: false
      matrix:
        branch: [modal, hetzner]
    runs-on: ubuntu-latest
    steps:
      - name: Generate token
        id: create_token
        uses: tibdex/github-app-token@v2
        with:
          app_id: ${{ secrets.APP_ID }}
          private_key: ${{ secrets.PRIVATE_KEY }}

      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          token: ${{ steps.create_token.outputs.token }}

      - name: Install uv
        uses: astral-sh/setup-uv@v4

      - name: Attempt merge and push, or open PR on conflict
        env:
          GH_TOKEN: ${{ steps.create_token.outputs.token }}
          BRANCH: ${{ matrix.branch }}
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

          open_propagation_pr() {
            TEMP_BRANCH="auto-merge/main-to-${BRANCH}-$(date +%Y%m%d%H%M%S)"
            git checkout -b "$TEMP_BRANCH" origin/main

            git push origin "$TEMP_BRANCH"

            gh pr create \
              --base "$BRANCH" \
              --head "$TEMP_BRANCH" \
              --title "Propagate main to ${BRANCH}" \
              --body "$(cat <<'PREOF'
          ## Summary
          - Auto-generated PR to propagate changes from `main` to the deployment branch
          - Opened because an automatic merge had conflicts that need manual resolution

          🤖 Generated by the propagate workflow
          PREOF
              )"
          }

          unresolved_conflicts() {
            git diff --name-only --diff-filter=U | sort
          }

          conflicts_are_modal_overlay() {
            [ "$BRANCH" = "modal" ] || return 1

            conflicts="$(unresolved_conflicts)"
            [ -n "$conflicts" ] || return 1

            while IFS= read -r file; do
              case "$file" in
                pyproject.toml|uv.lock) ;;
                *) return 1 ;;
              esac
            done <<< "$conflicts"
          }

          add_modal_dependency() {
            python3 <<'PY'
          from pathlib import Path
          import subprocess
          import tomllib

          def is_modal_dependency(dependency: str) -> bool:
              return dependency.split(";", 1)[0].strip().lower().startswith("modal")


          def modal_dependency_from_branch() -> str:
              try:
                  result = subprocess.run(
                      ["git", "show", ":2:pyproject.toml"],
                      check=True,
                      capture_output=True,
                      text=True,
                  )
              except subprocess.CalledProcessError:
                  return "modal>=0.73.162"

              dependencies = tomllib.loads(result.stdout).get("project", {}).get("dependencies", [])
              return next((dependency for dependency in dependencies if is_modal_dependency(dependency)), "modal>=0.73.162")


          path = Path("pyproject.toml")
          text = path.read_text()
          data = tomllib.loads(text)

          dependencies = data.get("project", {}).get("dependencies", [])
          if any(is_modal_dependency(dependency) for dependency in dependencies):
              raise SystemExit(0)

          lines = text.splitlines()
          start = next(
              (index for index, line in enumerate(lines) if line.strip() == "dependencies = ["),
              None,
          )
          if start is None:
              raise SystemExit("Could not find project dependencies in pyproject.toml")

          end = next(
              (index for index in range(start + 1, len(lines)) if lines[index].strip() == "]"),
              None,
          )
          if end is None:
              raise SystemExit("Could not find end of project dependencies in pyproject.toml")

          insert_at = end
          for index in range(start + 1, end):
              if lines[index].strip().startswith('"psycopg2-binary'):
                  insert_at = index
                  break

          lines.insert(insert_at, f'    "{modal_dependency_from_branch()}",')
          path.write_text("\n".join(lines) + "\n")
          PY
          }

          resolve_modal_overlay() {
            if unresolved_conflicts | grep -qx "pyproject.toml"; then
              git checkout --theirs pyproject.toml
            fi

            add_modal_dependency

            if unresolved_conflicts | grep -qx "uv.lock"; then
              git checkout --ours uv.lock
            fi

            uv lock
            git add pyproject.toml uv.lock

            remaining_conflicts="$(unresolved_conflicts)"
            if [ -n "$remaining_conflicts" ]; then
              echo "Conflicts remain after modal overlay resolution:"
              echo "$remaining_conflicts"
              return 1
            fi

            git commit --no-edit
            git push origin "$BRANCH"
          }

          git checkout "$BRANCH"

          if git merge origin/main --no-edit; then
            echo "Merge succeeded, pushing to $BRANCH"
            git push origin "$BRANCH"
          elif conflicts_are_modal_overlay; then
            echo "Merge conflict only affects the modal dependency overlay; resolving automatically"
            resolve_modal_overlay
          else
            echo "Merge conflict detected, opening PR"
            git merge --abort
            open_propagation_pr
          fi