[GHF] More verbose failures messages (#71941)

Summary:
Modify _check_output to capture `CalledProcessError` and add
stdout/stderr to the failure message
Also record github actions run id in the failure message (calculated based on `${{ github.run_id}}`)

Pull Request resolved: https://github.com/pytorch/pytorch/pull/71941

Reviewed By: seemethere

Differential Revision: D33829633

Pulled By: malfet

fbshipit-source-id: 060b2856ca6c71574075effa72b982f9e1d64e6e
(cherry picked from commit a9ad7df9b540f9ab14524a644cab5e06225debe4)

.github/scripts/gitutils.py

@@ -30,8 +30,18 @@ def fuzzy_list_to_dict(items: List[Tuple[str, str]]) -> Dict[str, List[str]]:
 
 
 def _check_output(items: List[str], encoding: str = "utf-8") -> str:
-    from subprocess import check_output
-    return check_output(items).decode(encoding)
+    from subprocess import check_output, CalledProcessError
+    try:
+        return check_output(items).decode(encoding)
+    except CalledProcessError as e:
+        msg = f"Command `{' '.join(e.cmd)}` returned non-zero exit code {e.returncode}"
+        stdout = e.stdout.decode(encoding) if e.stdout is not None else ""
+        stderr = e.stderr.decode(encoding) if e.stderr is not None else ""
+        if len(stderr) == 0:
+            msg += f"\n{stdout}"
+        else:
+            msg += f"\nstdout:\n{stdout}\nstderr:\n{stderr}"
+        raise RuntimeError(msg) from e
 
 
 class GitCommit:

.github/scripts/trymerge.py

@@ -411,7 +411,11 @@ def main() -> None:
         try:
             try_revert(repo, pr, dry_run=args.dry_run)
         except Exception as e:
-            gh_post_comment(org, project, args.pr_num, f"Reverting PR {args.pr_num} failed due to {e}", dry_run=args.dry_run)
+            msg = f"Reverting PR {args.pr_num} failed due to {e}"
+            run_url = os.getenv("GH_RUN_URL")
+            if run_url is not None:
+                msg += f"\nRaised by {run_url}"
+            gh_post_comment(org, project, args.pr_num, msg, dry_run=args.dry_run)
         return
 
     if pr.is_closed():
@@ -425,7 +429,11 @@ def main() -> None:
     try:
         pr.merge_into(repo, dry_run=args.dry_run)
     except Exception as e:
-        gh_post_comment(org, project, args.pr_num, f"Merge failed due to {e}", dry_run=args.dry_run)
+        msg = f"Merge failed due to {e}"
+        run_url = os.getenv("GH_RUN_URL")
+        if run_url is not None:
+            msg += f"\nRaised by {run_url}"
+        gh_post_comment(org, project, args.pr_num, msg, dry_run=args.dry_run)
 
 
 if __name__ == "__main__":

.github/workflows/revert.yml

@@ -27,5 +27,6 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.MERGEBOT_TOKEN }}
           PR_NUM: ${{ github.event.client_payload.pr_num }}
+          GH_RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
         run: |
           python3 .github/scripts/trymerge.py --revert "${PR_NUM}"

.github/workflows/trymerge.yml

@@ -27,5 +27,6 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.MERGEBOT_TOKEN }}
           PR_NUM: ${{ github.event.client_payload.pr_num }}
+          GH_RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
         run: |
           python3 .github/scripts/trymerge.py "${PR_NUM}"