pr-backport-autotrigger.yml

name: Backport on Merge

on:
  pull_request:
    types: [closed]  # Later we check for merge so only PRs that go in can get backported

permissions:
  contents: write
  actions: write  # Allows the workflow to trigger other workflows on push

jobs:
  backport:
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v3
        with:
          fetch-depth: 0  # Fetch all history for all branches and tags

      - name: Set up Git
        run: |
          git config --global user.name "yuhongsun96"
          git config --global user.email "yuhongsun96@gmail.com"
          # Configure Git to use the PAT for authentication
          git remote set-url origin https://yuhongsun96:${{ secrets.YUHONG_GH_ACTIONS }}@github.com/${{ github.repository }}.git

      - name: Check for Backport Checkbox
        id: checkbox-check
        run: |
          PR_BODY="${{ github.event.pull_request.body }}"
          if [[ "$PR_BODY" == *"[x] This PR should be backported"* ]]; then
            echo "backport=true" >> $GITHUB_OUTPUT
          else
            echo "backport=false" >> $GITHUB_OUTPUT
          fi

      - name: List and sort release branches
        id: list-branches
        run: |
          git fetch --all --tags
          BRANCHES=$(git for-each-ref --format='%(refname:short)' refs/remotes/origin/release/* | sed 's|origin/release/||' | sort -Vr)
          BETA=$(echo "$BRANCHES" | head -n 1)
          STABLE=$(echo "$BRANCHES" | head -n 2 | tail -n 1)
          echo "beta=release/$BETA" >> $GITHUB_OUTPUT
          echo "stable=release/$STABLE" >> $GITHUB_OUTPUT
          # Fetch latest tags for beta and stable
          LATEST_BETA_TAG=$(git tag -l "v*.*.0-beta.*" | sort -Vr | head -n 1)
          LATEST_STABLE_TAG=$(git tag -l "v*.*.*" | grep -v -- "-beta" | sort -Vr | head -n 1)
          # Increment latest beta tag
          NEW_BETA_TAG=$(echo $LATEST_BETA_TAG | awk -F '[.-]' '{print $1 "." $2 ".0-beta." ($NF+1)}')
          # Increment latest stable tag
          NEW_STABLE_TAG=$(echo $LATEST_STABLE_TAG | awk -F '.' '{print $1 "." $2 "." ($3+1)}')
          echo "latest_beta_tag=$LATEST_BETA_TAG" >> $GITHUB_OUTPUT
          echo "latest_stable_tag=$LATEST_STABLE_TAG" >> $GITHUB_OUTPUT
          echo "new_beta_tag=$NEW_BETA_TAG" >> $GITHUB_OUTPUT
          echo "new_stable_tag=$NEW_STABLE_TAG" >> $GITHUB_OUTPUT

      - name: Echo branch and tag information
        run: |
          echo "Beta branch: ${{ steps.list-branches.outputs.beta }}"
          echo "Stable branch: ${{ steps.list-branches.outputs.stable }}"
          echo "Latest beta tag: ${{ steps.list-branches.outputs.latest_beta_tag }}"
          echo "Latest stable tag: ${{ steps.list-branches.outputs.latest_stable_tag }}"
          echo "New beta tag: ${{ steps.list-branches.outputs.new_beta_tag }}"
          echo "New stable tag: ${{ steps.list-branches.outputs.new_stable_tag }}"

      - name: Trigger Backport
        if: steps.checkbox-check.outputs.backport == 'true'
        run: |
          set -e
          echo "Backporting to beta ${{ steps.list-branches.outputs.beta }} and stable ${{ steps.list-branches.outputs.stable }}"
          # Fetch all history for all branches and tags
          git fetch --prune
          # Checkout the beta branch
          git checkout ${{ steps.list-branches.outputs.beta }}
          # Cherry-pick the merge commit from the merged PR
          git cherry-pick -m 1 ${{ github.event.pull_request.merge_commit_sha }} || {
            echo "Cherry-pick to beta failed due to conflicts."
            exit 1
          }
          # Create new beta tag
          git tag ${{ steps.list-branches.outputs.new_beta_tag }}
          # Push the changes and tag to the beta branch
          git push origin ${{ steps.list-branches.outputs.beta }} --force
          git push origin ${{ steps.list-branches.outputs.new_beta_tag }}
          # Checkout the stable branch
          git checkout ${{ steps.list-branches.outputs.stable }}
          # Cherry-pick the merge commit from the merged PR
          git cherry-pick -m 1 ${{ github.event.pull_request.merge_commit_sha }} || {
            echo "Cherry-pick to stable failed due to conflicts."
            exit 1
          }
          # Create new stable tag
          git tag ${{ steps.list-branches.outputs.new_stable_tag }}
          # Push the changes and tag to the stable branch
          git push origin ${{ steps.list-branches.outputs.stable }} --force
          git push origin ${{ steps.list-branches.outputs.new_stable_tag }}