ci:check that type/docs-cherrypick is attached to website PR changes (#9690)

.github/workflows/pr-file-checker.yml

@@ -14,6 +14,7 @@ on:
       - release/*
 
 jobs:
+  # checks that a .changelog entry is present for a PR
   changelog-check:
     # If there  a `pr/no-changelog` label we ignore this check
     if: "!${{ contains(github.event.pull_request.label.*.name, 'pr/no-changelog')}}"
@@ -27,7 +28,7 @@ jobs:
       - name: Check for changelog entry in diff
         run: |
           # check if there is a diff in the .changelog directory
-          changelog_files=$(git --no-pager diff --name-only HEAD "$(git merge-base HEAD "${{ github.event.pull_request.base.ref }}")" -- .changelog/)
+          changelog_files=$(git --no-pager diff --name-only HEAD "$(git merge-base HEAD "origin/${{ github.event.pull_request.base.ref }}")" -- .changelog/)
 
           # If we do not find a file in .changelog/, we post a comment to the PR
           if [ -z "$changelog_files" ]; then
@@ -41,3 +42,30 @@ jobs:
           else
             echo "changelog-check: Found .changelog entry in PR!"
           fi
+
+  # checks that a 'type/docs-cherrypick' label is attached to PRs with website/ changes
+  website-check:
+    # If there's a `type/docs-cherrypick` label we ignore this check
+    if: "!${{ contains(github.event.pull_request.label.*.name, 'type/docs-cherrypick')}}"
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+          fetch-depth: 0 # by default the checkout action doesn't checkout all branches
+      - name: Check for website/ dir change in diff
+        run: |
+          # check if there is a diff in the website/ directory
+          website_files=$(git --no-pager diff --name-only HEAD "$(git merge-base HEAD "origin/${{ github.event.pull_request.base.ref }}")" -- website/)
+
+          # If we find changed files in the website/ directory, we post a comment to the PR
+          if [ -n "$website_files" ]; then
+            # post PR comment to GitHub to check if a 'type/docs-cherrypick' label needs to be applied to the PR
+            echo "website-check: Did not find a 'type/docs-cherrypick' label, posting a reminder in the PR"
+            github_message="🤔 This PR has changes in the `website/` directory but does not have a `type/docs-cherrypick` label. If the changes are for the next version, this can be ignored. If they are updates to current docs, attach the label to auto cherrypick to the `stable-website` branch after merging."
+            curl -f -s -H "Authorization: token ${{ secrets.PR_COMMENT_TOKEN }}" \
+                -X POST \
+                -d "{ \"body\": \"${github_message}\"}" \
+                "https://api.github.com/repos/${GITHUB_REPOSITORY}/issues/${{ github.event.pull_request.number }}/comments"
+          fi