Only tag merger if PR isn't properly labeled, not all reviewers (#4081)

Co-authored-by: Philip Meier <github.pmeier@posteo.de>

.github/process_commit.py

 """
-This script finds all responsible users for labeling a PR by a commit SHA. It is used by the workflow in
+This script finds the merger responsible for labeling a PR by a commit SHA. It is used by the workflow in
 '.github/workflows/pr-labels.yml'. If there exists no PR associated with the commit or the PR is properly labeled,
 this script is a no-op.
+
+Note: we ping the merger only, not the reviewers, as the reviewers can sometimes be external to torchvision
+with no labeling responsibility, so we don't want to bother them.
 """
 
 import sys
@@ -38,19 +41,6 @@ REQUIRED_LABELS = {
 }
 
 
-def find_responsible_users(commit_hash: str) -> Set[str]:
-    pr_number = get_pr_number(commit_hash)
-    if not pr_number:
-        return set()
-
-    merger, labels = get_pr_merger_and_labels(pr_number)
-    is_properly_labeled = bool(REQUIRED_LABELS.intersection(labels))
-    if is_properly_labeled:
-        return set()
-
-    return {merger, *get_pr_reviewers(pr_number)}
-
-
 def query_torchvision(cmd: str, *, accept) -> Any:
     response = requests.get(f"https://api.github.com/repos/pytorch/vision/{cmd}", headers=dict(Accept=accept))
     return response.json()
@@ -72,13 +62,14 @@ def get_pr_merger_and_labels(pr_number: int) -> Tuple[str, Set[str]]:
     return merger, labels
 
 
-def get_pr_reviewers(pr_number: int) -> Set[str]:
-    # See https://docs.github.com/en/rest/reference/pulls#list-reviews-for-a-pull-request
-    data = query_torchvision(f"pulls/{pr_number}/reviews", accept="application/vnd.github.v3+json")
-    return {review["user"]["login"] for review in data if review["state"] == "APPROVED"}
-
-
 if __name__ == "__main__":
     commit_hash = sys.argv[1]
-    users = find_responsible_users(commit_hash)
-    print(", ".join(sorted([f"@{user}" for user in users])))
+    pr_number = get_pr_number(commit_hash)
+    if not pr_number:
+        sys.exit(0)
+
+    merger, labels = get_pr_merger_and_labels(pr_number)
+    is_properly_labeled = bool(REQUIRED_LABELS.intersection(labels))
+
+    if not is_properly_labeled:
+        print(f"@{merger}")

.github/workflows/pr-labels.yml

@@ -19,17 +19,17 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
-      - name: Process commit and find users responsible for labeling
+      - name: Process commit and find merger responsible for labeling
         id: commit
-        run: echo "::set-output name=responsible_users::$(python .github/process_commit.py ${{ github.sha }})"
+        run: echo "::set-output name=merger::$(python .github/process_commit.py ${{ github.sha }})"
 
-      - name: Ping users responsible for labeling if necessary
-        if: ${{ steps.commit.outputs.responsible_users != '' }}
+      - name: Ping merger responsible for labeling if necessary
+        if: ${{ steps.commit.outputs.merger != '' }}
         uses: mshick/add-pr-comment@v1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           message: |
-            Hey ${{ steps.commit.outputs.responsible_users }}!
+            Hey ${{ steps.commit.outputs.merger }}!
 
-            You approved or merged this PR, but no labels were added.
+            You merged this PR, but no labels were added.