Fixes Glance Registry V2 client

Add an optional configuration step to glance.db.get_api().

This step is then used in glance.db.registry.api in order to ensure that
the registry client has been configured in time for the registry db
driver's use.

Closes bug: #1302345

Change-Id: Id2c52c423b411ec20bdfa76ee91837c98b1613ef
Co-Authored-By: Mark J. Washenberger <mark.washenberger@markwash.net>

Author: Erno Kuvaja

glance/db/__init__.py

@@ -31,7 +31,10 @@
 
 
 def get_api():
-    return importutils.import_module(CONF.data_api)
+    api = importutils.import_module(CONF.data_api)
+    if hasattr(api, 'configure'):
+        api.configure()
+    return api
 
 
 def unwrap(db_api):

glance/db/registry/api.py

@@ -37,6 +37,10 @@
 LOG = logging.getLogger(__name__)
 
 
+def configure():
+    api.configure_registry_client()
+
+
 def _get_client(func):
     """Injects a client instance to the each function
 

glance/tests/functional/db/test_registry.py

@@ -13,17 +13,16 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import glance.db.registry.api
-from glance.registry.client.v2 import api
+import glance.db
 from glance.tests import functional
 import glance.tests.functional.db as db_tests
 from glance.tests.functional.db import base
 
 
 def get_db(config):
     config(group='database', connection='sqlite://')
-    api.configure_registry_client()
-    return glance.db.registry.api
+    config(data_api='glance.db.registry.api')
+    return glance.db.get_api()
 
 
 def reset_db(db_api):

glance/tests/unit/test_db.py

@@ -16,6 +16,7 @@
 
 import uuid
 
+import mock
 from oslo.config import cfg
 
 from glance.common import crypt
@@ -29,6 +30,28 @@
 CONF = cfg.CONF
 CONF.import_opt('metadata_encryption_key', 'glance.common.config')
 
+
+@mock.patch('glance.openstack.common.importutils.import_module')
+class TestDbUtilities(test_utils.BaseTestCase):
+    def setUp(self):
+        super(TestDbUtilities, self).setUp()
+        self.config(data_api='silly pants')
+        self.api = mock.Mock()
+
+    def test_get_api_calls_configure_if_present(self, import_module):
+        import_module.return_value = self.api
+        self.assertEqual(glance.db.get_api(), self.api)
+        import_module.assert_called_once_with('silly pants')
+        self.api.configure.assert_called_once_with()
+
+    def test_get_api_skips_configure_if_missing(self, import_module):
+        import_module.return_value = self.api
+        del self.api.configure
+        self.assertEqual(glance.db.get_api(), self.api)
+        import_module.assert_called_once_with('silly pants')
+        self.assertFalse(hasattr(self.api, 'configure'))
+
+
 UUID1 = 'c80a1a6c-bd1f-41c5-90ee-81afedb1d58d'
 UUID2 = 'a85abd86-55b3-4d5b-b0b4-5d0a6e6042fc'
 UUID3 = '971ec09a-8067-4bc8-a91f-ae3557f1c4c7'