.github/workflows/cp-trigger.yml

# Copyright 2023 The Flutter Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# Unprivileged half of the cherry-pick automation.
#
# This workflow runs on `pull_request` with a read-only token and no access to
# secrets. When a `cp: beta` or `cp: stable` label is applied, it records the
# pull request number and channel in a `cp-metadata` artifact. The privileged
# `easy-cp.yml` workflow consumes that artifact via `workflow_run`, validates
# the request, and either performs the cherry-pick or comments on the pull
# request explaining why it can't.

name: Cherry-pick Trigger

on:
  pull_request:
    branches: [master]
    types: [labeled]

permissions:
  contents: read

jobs:
  record:
    name: Record cherry-pick request
    runs-on: ubuntu-latest
    # Evaluated before a runner is allocated, so other labels cost nothing.
    if: >-
      github.repository == 'flutter/flutter' &&
      (github.event.label.name == format('cp{0} beta', ':') || github.event.label.name == format('cp{0} stable', ':'))
    steps:
      - name: Record PR number and channel
        env:
          LABEL_NAME: ${{ github.event.label.name }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
        run: |
          mkdir -p cp-metadata
          CHANNEL=$(echo "$LABEL_NAME" | cut -d ':' -f 2 | xargs)
          jq -n --arg pr "$PR_NUMBER" --arg channel "$CHANNEL" \
            '{pr_number: $pr, channel: $channel}' > cp-metadata/metadata.json

      - name: Upload cherry-pick metadata
        uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
        with:
          name: cp-metadata
          path: cp-metadata/
          retention-days: 1
          if-no-files-found: error