3021: Propagate unhandled exceptions back to the caller instead of returning None...

[arvados.git] / sdk / python / arvados / errors.py

diff --git a/sdk/python/arvados/errors.py b/sdk/python/arvados/errors.py
index 85472d8cdf0bcb729933709aa7aee4d45a8df18e..16f4096572c422cf37a93a7110b19c45aa8f1061 100644 (file)
--- a/sdk/python/arvados/errors.py
+++ b/sdk/python/arvados/errors.py
@@ -1,16 +1,72 @@
 # errors.py - Arvados-specific exceptions.
 
+import json
+import requests
+
+from apiclient import errors as apiclient_errors
+from collections import OrderedDict
+
+class ApiError(apiclient_errors.HttpError):
+    def _get_reason(self):
+        try:
+            return '; '.join(json.loads(self.content)['errors'])
+        except (KeyError, TypeError, ValueError):
+            return super(ApiError, self)._get_reason()
+
+
+class KeepRequestError(Exception):
+    """Base class for errors accessing Keep services."""
+    def __init__(self, message='', service_errors=()):
+        """KeepRequestError(message='', service_errors=())
+
+        Arguments:
+        * message: A human-readable message describing what Keep operation
+          failed.
+        * service_errors: An iterable that yields 2-tuples of Keep
+          service URLs to the error encountered when talking to
+          it--either an exception, or an HTTP response object.  These
+          will be packed into an OrderedDict, available through the
+          service_errors() method.
+        """
+        self._service_errors = OrderedDict(service_errors)
+        if self._service_errors:
+            exc_reports = [self._format_error(*err_pair)
+                           for err_pair in self._service_errors.iteritems()]
+            base_msg = "{}: {}".format(message, "; ".join(exc_reports))
+        else:
+            base_msg = message
+        super(KeepRequestError, self).__init__(base_msg)
+        self.message = message
+
+    def _format_error(self, service_root, error):
+        if isinstance(error, requests.Response):
+            err_fmt = "{} responded with {e.status_code} {e.reason}"
+        else:
+            err_fmt = "{} raised {e.__class__.__name__} ({e})"
+        return err_fmt.format(service_root, e=error)
+
+    def service_errors(self):
+        """service_errors() -> OrderedDict
+
+        The keys of the dictionary are Keep service URLs.
+        The corresponding value is the exception raised when sending the
+        request to it."""
+        return self._service_errors
+
+
 class ArgumentError(Exception):
     pass
 class SyntaxError(Exception):
     pass
 class AssertionError(Exception):
     pass
-class NotFoundError(Exception):
-    pass
 class CommandFailedError(Exception):
     pass
-class KeepWriteError(Exception):
+class KeepReadError(KeepRequestError):
+    pass
+class KeepWriteError(KeepRequestError):
+    pass
+class NotFoundError(KeepReadError):
     pass
 class NotImplementedError(Exception):
     pass
@@ -18,3 +74,5 @@ class NoKeepServersError(Exception):
     pass
 class StaleWriterStateError(Exception):
     pass
+class FeatureNotEnabledError(Exception):
+    pass