vercel__next.js/.github/workflows/pr_stack_optimizer.yml

# Avoid running the full CI on mid-stack PRs: https://graphite.dev/docs/stacking-and-ci
#
# This supports both Graphite stacks and GitHub's native stacked PRs. For either kind of stack, we
# only run the full CI on the very top and very bottom of the stack.
#
# We still run some high-signal low-cost jobs (e.g. lint, unit tests) on mid-stack PRs, just not
# anything slow (e.g. integration tests).
#
# Because we don't use Graphite's CI batching, full CI will still run on every PR individually
# before it merges. The goal is just to avoid wasting CI capacity when frequently rebasing large
# stacks.
#
# This can by bypassed by labeling a PR with 'CI Bypass PR Stack Optimization' (or the legacy
# 'CI Bypass Graphite Optimization' label), and manually re-running CI.

name: PR Stack Optimizer
on:
  workflow_call:
    outputs:
      skip:
        description: "'true' if expensive CI checks should be skipped, 'false' otherwise."
        value: ${{ jobs.optimize-ci.outputs.skip }}
    secrets:
      GRAPHITE_CI_OPTIMIZER_TOKEN:
        description: 'The Graphite CI optimization secret'
        # secrets are not available in forks, check-skip will just fail-open with a warning
        required: false
env:
  # FYI, if you add this label, you must *push* to the repository again to trigger a new event. Just
  # re-running in the GitHub actions UI won't work, as it will re-use the old event with the old
  # labels.
  HAS_BYPASS_LABEL: |-
    ${{
      github.event_name == 'pull_request' &&
      (
        contains(github.event.pull_request.labels.*.name, 'CI Bypass PR Stack Optimization') ||
        contains(github.event.pull_request.labels.*.name, 'CI Bypass Graphite Optimization')
      )
    }}
  # GitHub's native stacked PRs expose the PR's position within the stack. We skip expensive CI on
  # mid-stack PRs. Fail open if we don't have `stack.size`.
  IS_MID_STACK_NATIVE: |-
    ${{
      github.event_name == 'pull_request' &&
      github.event.pull_request.stack.size != '' &&
      github.event.pull_request.stack.position != 1 &&
      github.event.pull_request.stack.position != github.event.pull_request.stack.size
    }}
jobs:
  optimize-ci:
    name: PR Stack Optimizer
    runs-on: ubuntu-latest
    outputs:
      # `== 'true'` comparison: If `step.check-skip` fails (`continue-on-error`), that output will
      # be an empty string, which sets our `skip` output to `'false'`.
      #
      # We skip if either Graphite's optimizer says to skip, or the PR is a mid-stack PR in a
      # GitHub native stack. The bypass label overrides both.
      skip: ${{ env.HAS_BYPASS_LABEL == 'false' && steps.check-skip.outputs.skip == 'true' }}
      # Note: IS_MID_STACK_NATIVE is disabled for now because it doesn't
      # understand if we're not on the bottom of the stack, but all the PRs
      # below us are merged.
      # <https://vercel.slack.com/archives/C04KC8A53T7/p1783018076576349>
      #  || env.IS_MID_STACK_NATIVE == 'true'
    steps:
      - name: Optimize CI
        id: check-skip
        # Graphite's action is designed to fail open, but still sometimes fails if GH's infra flakes
        continue-on-error: true
        uses: withgraphite/graphite-ci-action@402a89bc8aa6db18ae1f9c61953d001d5f9d828f # main
        with:
          graphite_token: ${{ secrets.GRAPHITE_CI_OPTIMIZER_TOKEN }}
      - name: Debug Output
        run: |
          echo 'github.event_name: ${{ github.event_name }}'
          echo "secrets.GRAPHITE_CI_OPTIMIZER_TOKEN != '': ${GRAPHITE_CI_OPTIMIZER_TOKEN_NON_EMPTY}"
          echo 'env.HAS_BYPASS_LABEL: ${{ env.HAS_BYPASS_LABEL }}'
          echo 'env.IS_MID_STACK_NATIVE: ${{ env.IS_MID_STACK_NATIVE }}'
          echo 'github.event.pull_request.stack.position: ${{ github.event.pull_request.stack.position }}'
          echo 'github.event.pull_request.stack.size: ${{ github.event.pull_request.stack.size }}'
          echo 'steps.check-skip.outputs.skip: ${{ steps.check-skip.outputs.skip }}'

        env:
          GRAPHITE_CI_OPTIMIZER_TOKEN_NON_EMPTY: ${{ secrets.GRAPHITE_CI_OPTIMIZER_TOKEN != '' }}