backport.yml

name: backport

on:
  push:
    branches:
      - 'main'

jobs:
  backport-target-branch:
    runs-on: ubuntu-latest
    outputs:
      matrix: ${{ steps.milestones.outputs.matrix }}
      latest_commit: ${{ steps.commit.outputs.latest_commit }}
      commit_message: ${{ steps.commit.outputs.commit_message }}
      pr_number: ${{ steps.commit.outputs.pr_number }}
      latest_release: ${{ steps.commit.outputs.latest_release }}
      author: ${{ steps.commit.outputs.author }}
      author_email: ${{ steps.commit.outputs.author_email }}
    steps:
      - name: Checkout the revision
        uses: actions/checkout@v4
        with:
          lfs: false
      - name: Extract pr_number from commit message
        id: commit
        run: |
          latest_commit=$(git rev-parse HEAD)  # Get the recent commit hash of the current repository
          echo "latest_commit=$latest_commit" >> $GITHUB_OUTPUT
          commit_message=$(git show -s --format=%B $latest_commit)  # Get messages from recent commit
          echo "commit_message<<EOF" >> $GITHUB_OUTPUT
          echo "$commit_message" >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT
          pr_number=$(echo $commit_message | grep -oP "\(#\d+\)" | grep -oP "\d+")  # Get pr number from commit message
          echo "pr_number=$pr_number" >> $GITHUB_OUTPUT
          latest_release=$(cat VERSION | grep -oP "\d+\.\d+")
          echo "latest_release=$latest_release" >> $GITHUB_OUTPUT
          author=$(git show -s --format=%an $latest_commit)
          echo "author=$author" >> $GITHUB_OUTPUT
          author_email=$(git show -s --format=%ae $latest_commit)
          echo "author_email=$author_email" >> $GITHUB_OUTPUT
      - name: Check if this is a merged pr commit
        run: |
          if [[ -z "${{ steps.commit.outputs.pr_number }}" ]]; then
            echo "This is not a merge commit of a PR."
            exit 0
          fi
          # Modified in a way to terminate without failure indication
      - name: Get target milestones
        id: milestones
        run: |
          target_milestone=$(gh pr view ${{ steps.commit.outputs.pr_number }} --json milestone --jq .milestone.title)

          milestones=$(gh api /repos/:owner/:repo/milestones --jq '.[].title')
          echo $milestones

          # Remove Backlog from the backport target branch
          milestones=($milestones)
          for i in "${!milestones[@]}"; do
            if [[ "${milestones[$i]}" == "Backlog" ]]; then
              unset 'milestones[$i]'
            fi
          done
          echo "${milestones[@]}"

          for i in "${!milestones[@]}"; do
            if ! git ls-remote --heads | grep -q "refs/heads/${milestones[$i]}\$"; then
              unset 'milestones[$i]'
            fi
          done
          echo "${milestones[@]}"

          sort_milestones=($(printf "%s\n" "${milestones[@]}" | sort -r))
          echo "${sort_milestones[@]}"
          for i in "${!sort_milestones[@]}"; do
            if [[ "${sort_milestones[$i]}" == "$target_milestone" ]]; then
              target_milestones=("${sort_milestones[@]:0:$((i+1))}")
              break
            fi
          done
          matrix=$(jq -nc '{include: $ARGS.positional | map_values({milestone: .})}' --args "${target_milestones[@]}")
          echo "matrix=$matrix" >> $GITHUB_OUTPUT
        env:
          GH_TOKEN: ${{ github.token }}

  backport:
    runs-on: ubuntu-latest
    needs: backport-target-branch
    strategy:
      matrix: ${{ fromJson(needs.backport-target-branch.outputs.matrix) }}
    permissions:
      pull-requests: write
    steps:
      - uses: actions/checkout@v4
        with:
          ref: ${{ matrix.milestone }}
      - name: Cherry-pick
        run: |
          git config --global user.name "${{ needs.backport-target-branch.outputs.author }}"
          git config --global user.email "${{ needs.backport-target-branch.outputs.author_email }}"
          git fetch origin main --depth=10
          git cherry-pick --strategy=recursive --strategy-option=theirs ${{ needs.backport-target-branch.outputs.latest_commit }}
          git commit \
            --amend -m '${{ needs.backport-target-branch.outputs.commit_message }}' \
            --trailer "Backported-from=main (${{ needs.backport-target-branch.outputs.latest_release }})" \
            --trailer "Backported-to=${{ matrix.milestone }}" \
            --trailer "Backport-of=${{ needs.backport-target-branch.outputs.pr_number }}"
      - name: When cherry-pick is failed
        if: failure()
        run: |
          gh pr comment ${{ needs.backport-target-branch.outputs.pr_number }} -b "Backport to ${{ matrix.milestone }} is failed. Please backport manually."
        env:
          GH_TOKEN: ${{ github.token }}
      - id: commit_message
        run: |
          commit_header=$(echo '${{ needs.backport-target-branch.outputs.commit_message }}' | head -n 1)
          echo "commit_header=$commit_header" >> $GITHUB_OUTPUT
          commit_body=$(echo '${{ needs.backport-target-branch.outputs.commit_message }}' | awk '/^$/{p++;next} p==1')
          echo "commit_body<<EOF" >> $GITHUB_OUTPUT
          echo "$commit_body" >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT
          commit_footer=$(echo '${{ needs.backport-target-branch.outputs.commit_message }}' | awk '/^$/{p++;next} p==2')
          echo "commit_footer<<EOF" >> $GITHUB_OUTPUT
          echo "$commit_footer" >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT
      - name: Create Bakport PR
        id: pr
        uses: peter-evans/create-pull-request@v6
        with:
          token: ${{ secrets.OCTODOG }}
          author: "${{ needs.backport-target-branch.outputs.author }} <${{ needs.backport-target-branch.outputs.author_email }}>"
          title: "${{ steps.commit_message.outputs.commit_header }}"
          body: "This is an auto-generated backport PR of #${{ needs.backport-target-branch.outputs.pr_number }} to the ${{ matrix.milestone }} release."
          branch: "backport/${{ needs.backport-target-branch.outputs.pr_number }}-to-${{ matrix.milestone }}"
          base: ${{ matrix.milestone }}
          labels: backport
          assignees: ${{ needs.backport-target-branch.outputs.author }}
      - run: |
          gh pr view ${{ needs.backport-target-branch.outputs.pr_number }} --json labels | jq -r '.labels[].name' | xargs -I {} gh pr edit ${{ steps.pr.outputs.pull-request-number }} --add-label {}
      - id: pr_id
        run: |
          pr_id=$(gh api graphql -f query='
            query ($pr_number: Int!, $owner: String!, $name: String!) {
              repository(owner: $owner, name: $name) {
                pullRequest(number: $pr_number) {
                  id
                }
              }
            }
          ' -F pr_number=${{ steps.pr.outputs.pull-request-number }} -f owner=${{ github.repository_owner }} -f name=${{ github.event.repository.name }} | jq -r '.data.repository.pullRequest.id')
          echo "pr_id=$pr_id" >> $GITHUB_OUTPUT
        env:
          GH_TOKEN: ${{ secrets.OCTODOG }}
      - id: commit_footer
        run: |
          commit_footer="Co-authored-by: ${{ needs.backport-target-branch.outputs.author }} <${{ needs.backport-target-branch.outputs.author_email }}>
          ${{ steps.commit_message.outputs.commit_footer }}
          Backported-from: main (${{ needs.backport-target-branch.outputs.latest_release }})
          Backported-to: ${{ matrix.milestone }}
          Backport-of: ${{ needs.backport-target-branch.outputs.pr_number }}"
          commit_footer=$(echo "$commit_footer" | grep '.')  # remove empty lines
          echo "commit_footer<<EOF" >> $GITHUB_OUTPUT
          echo "$commit_footer" >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT
      - name: Enable auto-merge
        if: ${{ steps.pr.outputs.pull-request-number }}
        run: |
          gh api graphql -f query='
            mutation ($pullRequestId: ID!, $mergeMethod: PullRequestMergeMethod!) {
              enablePullRequestAutoMerge(input: {
                pullRequestId: $pullRequestId,
                mergeMethod: $mergeMethod,
                commitBody: """
          ${{ steps.commit_message.outputs.commit_body }}

          ${{ steps.commit_footer.outputs.commit_footer }}
                """,
                commitHeadline: "${{ steps.commit_message.outputs.commit_header }} (#${{ steps.pr.outputs.pull-request-number }})"
              }) {
                pullRequest {
                  autoMergeRequest {
                    enabledAt
                  }
                }
              }
            }
          ' -F pullRequestId=${{ steps.pr_id.outputs.pr_id }} -f mergeMethod="SQUASH"
        env:
          GH_TOKEN: ${{ secrets.OCTODOG }}