apply-hotfix.yaml

name: Apply hotfix to branch
on:
  workflow_dispatch:
    inputs:
      pr_number:
        description: 'Number of merged pull request containing the hotfix.'
        required: true
      branch_name:
        description: 'Name of branch (release/* or rc/*) to apply hotfix to. Defaults to latest release branch.'

jobs:
  resolve-branch:
    runs-on: ubuntu-latest
    outputs:
      branch_name: ${{ steps.resolve_branch.outputs.branch_name }}
      branch_type: ${{ steps.resolve_branch.outputs.branch_type }}
    steps:
      - name: Check out hosted repo
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Resolve branch name
        id: resolve_branch
        run: |
          if [ "${{ github.event.inputs.branch_name }}" != "" ]; then
            branch_name="${{ github.event.inputs.branch_name }}"
          else
            branch_name=$(git branch -r --list 'release/*' | sort -r | head -n 1 | xargs)
          fi

          if [ -z "$branch_name" ]; then
            echo "No release branch found."
            exit 1
          fi

          branch_type=$(echo $branch_name | awk -F'[-/]' '{print $1}' )

          echo "branch_name=$branch_name" >> $GITHUB_OUTPUT
          echo "branch_type=$branch_type" >> $GITHUB_OUTPUT

  create-hotfix-pr:
    runs-on: ubuntu-latest
    needs:
      - resolve-branch
    permissions:
      contents: write
      pull-requests: write
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Checkout branch
        run: git checkout ${{ needs.resolve-branch.outputs.branch_name }}

      - name: Get merge commit SHA
        id: get_merge_commit_sha
        run: |
          MERGE_COMMIT_SHA=$(gh api repos/${{ github.repository }}/pulls/${{ github.event.inputs.pr_number }} --jq '.merge_commit_sha')
          echo "Merge commit SHA: $MERGE_COMMIT_SHA"
          echo "MERGE_COMMIT_SHA=$MERGE_COMMIT_SHA" >> $GITHUB_OUTPUT
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Set up Git
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

      - name: Attempt cherry-pick
        run: |
          BRANCH_NAME="hotfix-${{ github.event.inputs.pr_number }}/${{ needs.resolve-branch.outputs.branch_name }}"
          echo "BRANCH_NAME=$BRANCH_NAME" >> $GITHUB_ENV
          git checkout -b $BRANCH_NAME

          set +e
          git cherry-pick ${{ steps.get_merge_commit_sha.outputs.MERGE_COMMIT_SHA }} -m 1
          status=$?
          set -e

          if [ $status -eq 0 ]; then
            echo "Cherry-pick succeeded."
          else
            echo "Cherry-pick resulted in merge conflicts. Committing conflicts as-is."
            git add -A
            # Commit the conflicted state as-is. This will include conflict markers in the committed files.
            # The user will have to resolve them manually on the PR.
            git commit -m "Cherry-pick with conflicts: ${{ steps.get_merge_commit_sha.outputs.MERGE_COMMIT_SHA }}"
          fi

      - name: Push new branch
        run: |
          git push origin $BRANCH_NAME

      - name: Create Pull Request
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const baseBranch = "${{ needs.resolve-branch.outputs.branch_name }}"
            const headBranch = process.env.BRANCH_NAME
            const cherryCommit = "${{ steps.get_merge_commit_sha.outputs.MERGE_COMMIT_SHA }}"
            const assignee = context.actor
            const { data: pr } = await github.rest.pulls.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              title: `[HOTFIX] applying PR #${context.payload.inputs.pr_number} to ${{ needs.resolve-branch.outputs.branch_name}}`,
              head: headBranch,
              base: baseBranch,
              body: `This PR cherry-picks the commit ${cherryCommit} onto ${{ needs.resolve-branch.outputs.branch_name }}. If there are unresolved conflicts, please resolve them manually.`,
              assignees: [assignee],
              requested_reviewers: [assignee],
            })
            core.info(`Created PR #${pr.number}: ${pr.html_url}`)

            // Assign the PR to the user who triggered the workflow
            await github.rest.issues.addAssignees({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: pr.number,
              assignees: [assignee],
            })
            core.info(`Assigned PR #${pr.number} to ${assignee}`)

            // Request a review from the same user
            await github.rest.pulls.requestReviewers({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: pr.number,
              reviewers: [assignee]
            })
            core.info(`Requested review from ${assignee} on PR #${pr.number}`)