Simple merge queue (#22992)

.github/workflows/autoupdate-branch.yml

@@ -1,20 +1,22 @@
 name: Autoupdate branch
 
-# **What it does**: Any pull requests with automerge will get main branch updates.
-# **Why we have it**: So we don't have to watch pull requests and click update branch 100x.
+# **What it does**: The next pull request in the merge queue will get its
+# branch updated with main. Only updating one branch ensures that pull requests
+# in the queue are merged sequentially.
+# **Why we have it**: So we don't have to watch pull requests and click
+# update branch 1000x.
 # **Who does it impact**: Our health.
-
 #
-# This workflow checks all open PRs targeting `main` as their base branch and
-# will attempt to update them if they have automerge.
-# It is triggered when a `push` event occurs ON the `main` branch (e.g. a PR
-# was merged or a force-push was done).
+# The merge queue consists of any pull requests with automerge enabled and
+# are mergeable. There is a label that can be used to skip to the front of
+# the queue (`skip-to-front-of-merge-queue`).
 #
-# It should work on all PRs created from source branches within the repo itself
-# but is unlikely to work for PRs created from forked repos.
+# This workflow is triggered when a `push` event occurs ON the `main` branch
+#  (e.g. a PR was merged or a force-push was done).
 #
-# It is still worthwhile to leave it enabled for the `docs` open source repo as
-# it should at least be running on `repo-sync` branch PRs.
+# This workflow runs on all PRs created from source branches within the
+# public and private docs repos but is won't work for PRs created from
+# forked repos.
 #
 
 on:
@@ -28,8 +30,7 @@ jobs:
     name: autoupdate
     runs-on: ubuntu-latest
     steps:
-      - uses: docker://chinthakagodawita/autoupdate-action:v1
+      - name: Update next PR in queue
         env:
-          GITHUB_TOKEN: ${{ secrets.OCTOMERGER_PAT_WITH_REPO_AND_WORKFLOW_SCOPE }}
-          PR_FILTER: auto_merge
-          MERGE_MSG: 'Autoupdate branch'
+          GITHUB_TOKEN: ${{ secrets.DOCUBOT_REPO_PAT }}
+        run: node .github/actions-scripts/update-merge-queue-branch.js