fix: retry auth.TransportError errors (#418)

* fix: retry auth.TransportError's

* unwrap exceptions

* lint

* revert exceptions alias

* scope unwrapping and add unit test

* lint

* fix unit test

Author: frankyn

google/cloud/storage/retry.py

@@ -14,18 +14,19 @@
 
 import requests
 
-from google.api_core import exceptions
+from google.api_core import exceptions as api_exceptions
 from google.api_core import retry
+from google.auth import exceptions as auth_exceptions
 
 import json
 
 
 _RETRYABLE_TYPES = (
-    exceptions.TooManyRequests,  # 429
-    exceptions.InternalServerError,  # 500
-    exceptions.BadGateway,  # 502
-    exceptions.ServiceUnavailable,  # 503
-    exceptions.GatewayTimeout,  # 504
+    api_exceptions.TooManyRequests,  # 429
+    api_exceptions.InternalServerError,  # 500
+    api_exceptions.BadGateway,  # 502
+    api_exceptions.ServiceUnavailable,  # 503
+    api_exceptions.GatewayTimeout,  # 504
     requests.ConnectionError,
 )
 
@@ -37,8 +38,10 @@ def _should_retry(exc):
     """Predicate for determining when to retry."""
     if isinstance(exc, _RETRYABLE_TYPES):
         return True
-    elif isinstance(exc, exceptions.GoogleAPICallError):
+    elif isinstance(exc, api_exceptions.GoogleAPICallError):
         return exc.code in _ADDITIONAL_RETRYABLE_STATUS_CODES
+    elif isinstance(exc, auth_exceptions.TransportError):
+        return _should_retry(exc.args[0])
     else:
         return False
 

tests/unit/test_retry.py

@@ -25,7 +25,16 @@ def _call_fut(self, exc):
 
         return retry._should_retry(exc)
 
-    def test_w_retryable_types(self):
+    def test_w_retryable_transport_error(self):
+        from google.cloud.storage import retry
+        from google.auth.exceptions import TransportError as eTransportError
+        from requests import ConnectionError as rConnectionError
+
+        caught_exc = rConnectionError("Remote end closed connection unexpected")
+        exc = eTransportError(caught_exc)
+        self.assertTrue(retry._should_retry(exc))
+
+    def test_w_wrapped_type(self):
         from google.cloud.storage import retry
 
         for exc_type in retry._RETRYABLE_TYPES: