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Scopes with Bazel

Configure merge queue scopes using Bazel's dependency graph for precise batching.

If you’re using monorepo tools like Bazel that have built-in dependency graph analysis, you can use their affected project detection instead of file patterns. This approach is often more accurate because these tools understand your project’s dependency relationships.

Configuring Manual Scopes

Section titled Configuring Manual Scopes

To use the manual scopes mechanism, configure Mergify to expect scopes from your CI system:

scopes:
  source:
    manual:


queue_rules:
  - name: default
    batch_size: 5

Detecting Scopes with Bazel

Section titled Detecting Scopes with Bazel

Use bazel query to determine affected projects and upload them to Mergify.

GitHub Actions

Section titled GitHub Actions
name: Detect Scopes
on:
  pull_request:


jobs:
  detect-scopes:
    runs-on: ubuntu-24.04
    steps:
      - uses: actions/checkout@v5
        with:
          # The queue-aware base commit must exist locally for `git diff`.
          fetch-depth: 0


      - name: Get git refs
        id: refs
        uses: Mergifyio/gha-mergify-ci@v25
        with:
          action: scopes-git-refs


      - name: Get scopes
        id: scopes
        env:
          HEAD: ${{ steps.refs.outputs.head }}
          BASE: ${{ steps.refs.outputs.base }}
        run: |
          changed=$(git diff --name-only --diff-filter=ACMR "$BASE" "$HEAD" | tr '\n' ' ')
          if [ -z "$changed" ]; then
            echo "scopes=" >> "$GITHUB_OUTPUT"
            exit 0
          fi


          set +e
          packages=$(bazel query --keep_going --noshow_progress --output=package \
            "buildfiles(set($changed))" 2>query.err)
          rc=$?
          set -e
          # --keep_going exits 3 when it skipped files outside any Bazel package
          # (README.md, .github/**). Anything else is a real failure and must not
          # be swallowed into an empty scope list.
          if [ "$rc" -ne 0 ] && [ "$rc" -ne 3 ]; then
            cat query.err >&2
            exit "$rc"
          fi


          scopes=$(printf '%s\n' "$packages" | sed '/^$/d' | sort -u | paste -sd, -)
          echo "Detected scopes: ${scopes:-<none>}"
          echo "scopes=$scopes" >> "$GITHUB_OUTPUT"


      - name: Scopes upload
        uses: Mergifyio/gha-mergify-ci@v25
        with:
          action: scopes-upload
          token: ${{ secrets.MERGIFY_TOKEN }}
          scopes: ${{ steps.scopes.outputs.scopes }}

Buildkite

Section titled Buildkite

Using the mergifyio/mergify-ci Buildkite plugin, a first step resolves the merge-queue-aware base and head SHAs and exposes them as meta-data, while a second step computes the affected projects with bazel query and uploads them to Mergify:

steps:
  - label: ":mag: Get git refs"
    key: git-refs
    plugins:
      - mergifyio/mergify-ci#v7:
          action: scopes-git-refs


  - label: ":mag: Detect and upload scopes"
    depends_on: git-refs
    command: |
      BASE=$(buildkite-agent meta-data get "mergify-ci.base")
      HEAD=$(buildkite-agent meta-data get "mergify-ci.head")
      CHANGED=$(git diff --name-only --diff-filter=ACMR "$BASE" "$HEAD" | tr '\n' ' ')
      SCOPES=""
      if [ -n "$CHANGED" ]; then
        set +e
        PACKAGES=$(bazel query --keep_going --noshow_progress --output=package \
          "buildfiles(set($CHANGED))" 2>query.err)
        RC=$?
        set -e
        # --keep_going exits 3 when it skipped files outside any Bazel package.
        # Anything else is a real failure, not an empty scope list.
        if [ "$RC" -ne 0 ] && [ "$RC" -ne 3 ]; then
          cat query.err >&2
          exit "$RC"
        fi
        SCOPES=$(printf '%s\n' "$PACKAGES" | sed '/^$/d' | sort -u | paste -sd, -)
      fi
      buildkite-agent meta-data set "mergify-ci.scopes" "$SCOPES"
    plugins:
      - mergifyio/mergify-ci#v7:
          action: scopes-upload
          token: "${MERGIFY_TOKEN}"

Any CI (Mergify CLI)

Section titled Any CI (Mergify CLI)

Install the Mergify CLI in your pipeline and export MERGIFY_TOKEN. Use mergify ci git-refs to get the merge-queue-aware base and head SHAs and mergify ci scopes-send to upload the detected scopes:

Terminal window
REFS=$(mergify ci git-refs --format json)
BASE=$(printf '%s' "$REFS" | jq -r '.base')
HEAD=$(printf '%s' "$REFS" | jq -r '.head')


CHANGED=$(git diff --name-only --diff-filter=ACMR "$BASE" "$HEAD" | tr '\n' ' ')


if [ -z "$CHANGED" ]; then
echo '{"scopes": []}' > scopes.json
else
# Capture the exit code rather than piping straight into jq: a failed query
# piped into jq still writes a well-formed, empty scopes.json and returns 0.
if PACKAGES=$(bazel query --keep_going --noshow_progress --output=package \
                "buildfiles(set($CHANGED))" 2>query.err); then
  RC=0
else
  RC=$?
fi


# --keep_going exits 3 when it skipped files outside any Bazel package
# (README.md, .github/**). Anything else is a real failure.
if [ "$RC" -ne 0 ] && [ "$RC" -ne 3 ]; then
  cat query.err >&2
  exit "$RC"
fi


printf '%s\n' "$PACKAGES" | sort -u \
  | jq -R -s '{scopes: split("\n") | map(select(length > 0))}' > scopes.json
fi


mergify ci scopes-send --scopes-json scopes.json

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