ghstack_rebase.yaml

# The rebase-command workflow runs rebase + ghstack submit on the PR
#
# This workflow is triggered by leaving a "/rebase" comment on
# a pull request. If the required preconditions are met, it will
# rebase a stack of PRs that includes the current one as well as
# all the PRs underneath it in the stack.
#
# Conditions are checked through the "ghstack-perm-check.py"
# python script defined in the .github/workflows/scripts folder.
#
# Condition for the "/rebase" command are:
# - the current PR is in the format generated by ghstack
# - either the issuer is the author of the PR
# - or the issuer is a maintainer
#
# The PRs are rebased by a bot account "fms-cibot" which has push
# permissions on the repo.
#
# When a rebase is executed successfully, the horray emoji is added
# When a rebase execution fails, a comment is added with a link to the logs

name: Rebase ghstack PRs
on:
  repository_dispatch:
    types: [rebase-command]

jobs:
  ghstack_rebase:
    name: ghstack Rebase
    runs-on: ubuntu-latest
    steps:
    - name: Show Environment Variables
      run: env
    - name: Show Github Object
      run: |
        cat <<'EOF'
        ${{ toJson(github) }}
        EOF
    - name: Show Github Event Path Json
      run: 'cat "$GITHUB_EVENT_PATH" || true'
    - uses: actions/checkout@v4
      with:
        token: ${{ secrets.LAND_TOKEN }}
        fetch-depth: '0'
    - uses: actions/setup-python@v4
      with:
        python-version: 3.9
    - name: Check Rebase Preconditions
      run: |
        pip install requests ghstack

        # Check prerequisites and set environment variables
        # IS_GHSTACK, REPO, PR_NUMBER, PR_REF, PR_URL, PR_FROM_FORK
        .github/workflows/scripts/ghstack-perm-check.py rebase <<'EOF'
        ${{ toJson(github) }}
        EOF
      env:
        GITHUB_TOKEN: ${{ secrets.LAND_TOKEN }}
    - name: Rebase It!
      id: rebaseStack
      run: |
        # Configure Git and GHStack
        # TODO: update the bot e-mail once a correct e-mail is available
        git config --global user.email "foundation-model-stack@googlegroups.com"
        git config --global user.name "Foundation Model Stack CI Bot"

        if [[ "${IS_GHSTACK}" == "True" ]]; then
          # Configure ghstack
          cat <<EOF > ~/.ghstackrc
          [ghstack]
          github_url = github.com
          github_oauth = $GITHUB_TOKEN
          github_username = afrittoli
          remote_name = origin
        EOF

          # Checkout the */orig committer branch for rebase
          # See https://github.com/ezyang/ghstack?tab=readme-ov-file#structure-of-submitted-pull-requests
          # This is equivalent to "ghstack checkout <pr>", but it doesn't require
          # extra API calls to GitHub
          git checkout -b rebase-branch "origin/${PR_REF}"
        else
          gh pr checkout --repo "${REPO}" "${PR_NUMBER}"
        fi

        # Do the actual rebase. Git rebase will exit with 1 in case or merge conflicts
        # The rebase command is the same for GHStack and GitHub PRs
        git rebase origin/main

        if [[ "${IS_GHSTACK}" == "True" ]]; then
          # Submit the rebased stack to updated the PRs
          ghstack submit
        else
          # Force-push is the only way to have a rebased branch upstream
          # In case of failure, check if the PR is from a fork. Depending
          # on how the PR is configured, push might not be possible for the bot
          # See https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/allowing-changes-to-a-pull-request-branch-created-from-a-fork
          if ! git push --force; then
            if [[ "${PR_FROM_FORK}" == "true" ]]; then
              echo "The PR has been created from a fork."
              echo "Please rebase your PR manually and push the updates to the branch on your fork."
              exit 1
            fi
          fi
        fi
      env:
        GITHUB_TOKEN: ${{ secrets.LAND_TOKEN }}

    - name: Create URL to the run output
      if: ${{ failure() && steps.rebaseStack.outcome == 'failure' }}
      id: vars
      run: echo "run-url=https://github.com/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID" >> $GITHUB_OUTPUT

    - name: Create comment
      if: ${{ failure() && steps.rebaseStack.outcome == 'failure' }}
      uses: peter-evans/create-or-update-comment@v2
      with:
        token: ${{ secrets.LAND_TOKEN }}
        repository: ${{ github.event.client_payload.github.payload.repository.full_name }}
        issue-number: ${{ github.event.client_payload.github.payload.issue.number }}
        body: |
          Something went wrong with your `/${{ github.event.client_payload.slash_command.command }}` command: [please check the logs][1].

          [1]: ${{ steps.vars.outputs.run-url }}

    - name: Add reaction
      if: ${{ success() }}
      uses: peter-evans/create-or-update-comment@v2
      with:
        token: ${{ secrets.LAND_TOKEN }}
        repository: ${{ github.event.client_payload.github.payload.repository.full_name }}
        comment-id: ${{ github.event.client_payload.github.payload.comment.id }}
        reaction-type: hooray