Add warning when GCS checkpoint is missing commit_success.txt (in cas…

…e the checkpoint comes from not GCS originally).

PiperOrigin-RevId: 658176355

checkpoint/orbax/checkpoint/path/step.py

@@ -540,6 +540,15 @@ def is_checkpoint_finalized(path: epath.PathLike) -> bool:
   if not path.is_dir():
     raise ValueError(f'Path {path} is not a directory. Not a valid checkpoint')
   if is_gcs_path(path) and not (path / _COMMIT_SUCCESS_FILE).exists():
+    logging.warning(
+        'This GCS path %s does not contain the file indicating a successfully '
+        ' written GCS checkpoint: %s. If the checkpoint was originally saved'
+        ' with GCS, the checkpoint was not successfully written. If the'
+        ' the checkpoint was saved differently and copied, you need to'
+        ' add %s to the checkpoint directory.', path, _COMMIT_SUCCESS_FILE,
+        _COMMIT_SUCCESS_FILE
+    )
+
     return False
   if TMP_DIR_SUFFIX in path.name:
     return False