add auto cherry-pick

.github/workflows/auto_docs.yml

@@ -1,26 +1,62 @@
-name: Push to docs-latest on merge
-
-# TODO(jan):
-# 1. trigger on push to `main`
-# 2. if the commit ends with (#\d+), that is the PR number
-# 3. find the PR by its number
-# 4. if the PR has the label `deploy-docs`, then push the commit
-#    to `docs-latest`
-# 5. once committed, send a comment to the PR:
-#    "`deploy-docs` label found, this PR has been deployed to `docs-latest`."
-#    ideally, also include a link to the deploy job on vercel.
+name: Docs deploy
 
 on:
-  pull_request_target:
-    types:
-      - closed
+  push:
+    branches: [main]
+
+permissions:
+  contents: "read"
+  id-token: "write"
+
+defaults:
+  run:
+    shell: bash
+
+# The lack of `concurrency` is intentional.
+# We want this job to run on every commit, even if multiple are merged in a row.
 
 jobs:
-  auto-docs:
-    if: ${{ github.event.pull_request.merged == true && contains(github.event.pull_request.labels.*.name, 'deploy docs') }}
+  has-label:
+    name: Check for PR label
+    runs-on: ubuntu-latest
+    outputs:
+      result: ${{ steps.find-pr.outputs.result }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          # ref - not set, because we want to end up on the merge commit
+          fetch-depth: 0 # don't perform a shallow clone
+
+      # Find the PR by the number in the merge commit subject line
+      - name: Find PR
+        id: find-pr
+        env:
+          GH_TOKEN: ${{ secrets.RERUN_BOT_TOKEN }}
+        run: |
+          commit_message=$(git log --pretty=format:%s -n 1 ${{ github.sha }})
+          pr_number=$(echo $commit_message | grep -oP '(?<=#)\d+')
+
+          result=$(gh pr view $pr_number --json labels | jq -r 'any(.labels[].name; . == "deploy docs")')
+          echo "result=$result" >> $GITHUB_OUTPUT
+
+  cherry-pick:
+    name: Cherry-pick to docs-latest
+    needs: [has-label]
+    if: needs.has-label.outputs.result == 'true'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
         with:
-          ref: docs-latest
           fetch-depth: 0
+          token: ${{ secrets.RERUN_BOT_TOKEN }}
+
+      - name: Cherry-pick
+        run: |
+          # Setup git user
+          git config --global user.name "rerun-bot"
+          git config --global user.email "[email protected]"
+
+          # Cherry-pick the commit
+          git checkout docs-latest
+          git cherry-pick ${{ github.sha }}
+          git push origin docs-latest