Raise an exception when quota config parameter is broken

Function get_remaining_quota returns None when quota config
param doesn't match a pattern (i.e. it's broken). It messes up 
the logic of its callers and leads to unpredictible behavior of 
the entire system.

This code raises InvalidOptionValue exception if config is broken

Change-Id: Ib08d2114f460d127aacf580fc519a58d6e8eba16

glance/api/common.py

@@ -115,10 +115,11 @@ def get_remaining_quota(context, db_api, image_id=None):
     match = pattern.match(users_quota)
 
     if not match:
-        LOG.warn(_LW("Invalid value for option user_storage_quota: "
-                     "%(users_quota)s")
-                 % {'users_quota': users_quota})
-        return None
+        LOG.error(_LE("Invalid value for option user_storage_quota: "
+                      "%(users_quota)s")
+                  % {'users_quota': users_quota})
+        raise exception.InvalidOptionValue(option='user_storage_quota',
+                                           value=users_quota)
 
     quota_value, quota_unit = (match.groups())[0:2]
     # fall back to Bytes if user specified anything other than
@@ -128,7 +129,7 @@ def get_remaining_quota(context, db_api, image_id=None):
     users_quota = int(quota_value) * factor
 
     if users_quota <= 0:
-        return None
+        return
 
     usage = db_api.user_get_storage_usage(context,
                                           context.owner,

glance/common/exception.py

@@ -163,6 +163,10 @@ class InvalidFilterRangeValue(Invalid):
     message = _("Unable to filter using the specified range.")
 
 
+class InvalidOptionValue(Invalid):
+    message = _("Invalid value for option %(option)s: %(value)s")
+
+
 class ReadonlyProperty(Forbidden):
     message = _("Attribute '%(property)s' is read-only.")
 

glance/tests/unit/test_quota.py

@@ -434,6 +434,12 @@ class TestImagePropertyQuotas(test_utils.BaseTestCase):
         self.assertNotIn('foo', self.base_image.extra_properties)
         self.assertEqual('ham', self.base_image.extra_properties['spam'])
 
+    def test_invalid_quota_config_parameter(self):
+        self.config(user_storage_quota='foo')
+        location = {"url": "file:///fake.img.tar.gz", "metadata": {}}
+        self.assertRaises(exception.InvalidOptionValue,
+                          self.image.locations.append, location)
+
     def test_exceed_quota_during_patch_operation(self):
         self._quota_exceed_setup()
         self.image.extra_properties['frob'] = 'baz'