Update EMC Manila driver framework using stevedore

Alternative way of registering plugins in EMC Manila driver framework
using the module *stevedore*.

Change-Id: I3c38a2dbc9575a81c83e64180cd37916abe68334
Implements: blueprint register-emc-manila-plugin-with-stevedore

manila/share/drivers/emc/driver.py

@@ -24,10 +24,7 @@ from oslo.config import cfg
 
 from manila.openstack.common import log
 from manila.share import driver
-from manila.share.drivers.emc.plugins import \
+from manila.share.drivers.emc import plugin_manager as manager
-    registry as emc_plugins_registry
-# TODO(jay.xu): Implement usage of stevedore for plugins.
-from manila.share.drivers.emc.plugins.vnx import connection    # noqa
 
 
 LOG = log.getLogger(__name__)
@@ -71,11 +68,14 @@ class EMCShareDriver(driver.ShareDriver):
         if self.configuration:
             self.configuration.append_config_values(EMC_NAS_OPTS)
 
-        self._storage_conn = None
+        self.plugin_manager = manager.EMCPluginManager(
+            namespace='manila.share.drivers.emc.plugins')
+
+        self.plugin = None
 
     def create_share(self, context, share, share_server=None):
         """Is called to create share."""
-        location = self._storage_conn.create_share(self, context, share,
+        location = self.plugin.create_share(self, context, share,
                                             share_server)
 
         return location
@@ -83,37 +83,37 @@ class EMCShareDriver(driver.ShareDriver):
     def create_share_from_snapshot(self, context, share, snapshot,
                                    share_server=None):
         """Is called to create share from snapshot."""
-        location = self._storage_conn.create_share_from_snapshot(
+        location = self.plugin.create_share_from_snapshot(
             self, context, share, snapshot, share_server)
 
         return location
 
     def create_snapshot(self, context, snapshot, share_server=None):
         """Is called to create snapshot."""
-        self._storage_conn.create_snapshot(self, context, snapshot,
+        self.plugin.create_snapshot(self, context, snapshot,
                                     share_server)
 
     def delete_share(self, context, share, share_server=None):
         """Is called to remove share."""
-        self._storage_conn.delete_share(self, context, share, share_server)
+        self.plugin.delete_share(self, context, share, share_server)
 
     def delete_snapshot(self, context, snapshot, share_server=None):
         """Is called to remove snapshot."""
-        self._storage_conn.delete_snapshot(self, context, snapshot,
+        self.plugin.delete_snapshot(self, context, snapshot,
                                     share_server)
 
     def ensure_share(self, context, share, share_server=None):
         """Invoked to sure that share is exported."""
-        self._storage_conn.ensure_share(self, context, share, share_server)
+        self.plugin.ensure_share(self, context, share, share_server)
 
     def allow_access(self, context, share, access, share_server=None):
         """Allow access to the share."""
-        self._storage_conn.allow_access(self, context, share, access,
+        self.plugin.allow_access(self, context, share, access,
                                  share_server)
 
     def deny_access(self, context, share, access, share_server=None):
         """Deny access to the share."""
-        self._storage_conn.deny_access(self, context, share, access,
+        self.plugin.deny_access(self, context, share, access,
                                 share_server)
 
     def check_for_setup_error(self):
@@ -122,9 +122,11 @@ class EMCShareDriver(driver.ShareDriver):
 
     def do_setup(self, context):
         """Any initialization the share driver does while starting."""
-        self._storage_conn = emc_plugins_registry.create_storage_connection(
+        backend_name = self.configuration.safe_get('emc_share_backend')
-            self.configuration.safe_get('emc_share_backend'), LOG)
+
-        self._storage_conn.connect(self, context)
+        self.plugin = self.plugin_manager.load_plugin(backend_name, LOG)
+
+        self.plugin.connect(self, context)
 
     def get_share_stats(self, refresh=False):
         """Get share stats.
@@ -152,19 +154,19 @@ class EMCShareDriver(driver.ShareDriver):
         data['free_capacity_gb'] = 'infinite'
         data['reserved_percentage'] = 0
         data['QoS_support'] = False
-        self._storage_conn.update_share_stats(data)
+        self.plugin.update_share_stats(data)
         self._stats = data
 
     def get_network_allocations_number(self):
         """Returns number of network allocations for creating VIFs."""
-        return self._storage_conn.get_network_allocations_number(self)
+        return self.plugin.get_network_allocations_number(self)
 
     def setup_server(self, network_info, metadata=None):
         """Set up and configures share server with given network parameters."""
-        return self._storage_conn.setup_server(self, network_info, metadata)
+        return self.plugin.setup_server(self, network_info, metadata)
 
     def teardown_server(self, server_details, security_services=None):
         """Teardown share server."""
-        return self._storage_conn.teardown_server(self,
+        return self.plugin.teardown_server(self,
                                            server_details,
                                            security_services)

manila/share/drivers/emc/plugin_manager.py

@@ -12,20 +12,20 @@
 #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #    License for the specific language governing permissions and limitations
 #    under the License.
-
 """EMC Share Driver Plugin Framework."""
-
+from stevedore import extension
-g_registered_storage_backends = {}
 
 
-def register_storage_backend(share_backend_name, storage_conn_class):
+class EMCPluginManager(object):
-    """register a backend storage plugins."""
+    def __init__(self, namespace):
-    g_registered_storage_backends[
+        self.namespace = namespace
-        share_backend_name.upper()] = storage_conn_class
 
+        self.extension_manager = extension.ExtensionManager(namespace)
 
-def create_storage_connection(share_backend_name, logger):
+    def load_plugin(self, name, logger=None):
-    """create an instance of plugins."""
+        for ext in self.extension_manager.extensions:
-    storage_conn_class = g_registered_storage_backends[
+            if ext.name == name:
-        share_backend_name.upper()]
+                storage_conn = ext.plugin(logger)
-    return storage_conn_class(logger)
+                return storage_conn
+
+        return None

manila/share/drivers/emc/plugins/vnx/connection.py

@@ -24,7 +24,6 @@ from manila.i18n import _LE
 from manila.i18n import _LW
 from manila.openstack.common import log
 from manila.share.drivers.emc.plugins import base as driver
-from manila.share.drivers.emc.plugins import registry
 from manila.share.drivers.emc.plugins.vnx import constants
 from manila.share.drivers.emc.plugins.vnx import helper
 from manila.share.drivers.emc.plugins.vnx import utils as vnx_utils
@@ -918,6 +917,3 @@ class VNXStorageConnection(driver.StorageConnection):
             msg = _("Only single security service with "
                     "type 'active_directory' supported")
             raise exception.EMCVnxXMLAPIError(err=msg)
-
-
-registry.register_storage_backend("vnx", VNXStorageConnection)

manila/tests/share/drivers/emc/test_driver.py

@@ -14,13 +14,12 @@
 #    under the License.
 
 import mock
+from stevedore import extension
 
 from manila.openstack.common import log as logging
 from manila.share import configuration as conf
 from manila.share.drivers.emc import driver as emcdriver
 from manila.share.drivers.emc.plugins import base
-from manila.share.drivers.emc.plugins import \
-    registry as emc_plugins_registry
 from manila import test
 
 LOG = logging.getLogger(__name__)
@@ -89,8 +88,20 @@ class FakeConnection(base.StorageConnection):
 FAKE_BACKEND = 'fake_backend'
 
 
+class FakeEMCExtensionManager():
+    def __init__(self):
+        self.extensions = []
+        self.extensions.append(
+            extension.Extension(name=FAKE_BACKEND,
+                                plugin=FakeConnection,
+                                entry_point=None,
+                                obj=None))
+
+
 class EMCShareFrameworkTestCase(test.TestCase):
 
+    @mock.patch('stevedore.extension.ExtensionManager',
+                mock.Mock(return_value=FakeEMCExtensionManager()))
     def setUp(self):
         super(EMCShareFrameworkTestCase, self).setUp()
         self.configuration = conf.Configuration(None)
@@ -101,18 +112,15 @@ class EMCShareFrameworkTestCase(test.TestCase):
             configuration=self.configuration)
 
     def test_driver_setup(self):
-        emc_plugins_registry.register_storage_backend(
-            FAKE_BACKEND, FakeConnection)
-
         FakeConnection.connect = mock.Mock()
         self.driver.do_setup(None)
-        self.assertIsInstance(self.driver._storage_conn, FakeConnection,
+        self.assertIsInstance(self.driver.plugin, FakeConnection,
                               "Not an instance of FakeConnection")
         FakeConnection.connect.assert_called_with(self.driver, None)
 
     def test_update_share_stats(self):
         data = {}
-        self.driver._storage_conn = mock.Mock()
+        self.driver.plugin = mock.Mock()
         self.driver._update_share_stats()
         data["share_backend_name"] = FAKE_BACKEND
         data["vendor_name"] = 'EMC'
@@ -122,8 +130,7 @@ class EMCShareFrameworkTestCase(test.TestCase):
         data['free_capacity_gb'] = 'infinite'
         data['reserved_percentage'] = 0
         data['QoS_support'] = False
-        self.driver._storage_conn.\
+        self.driver.plugin.update_share_stats.assert_called_with(data)
-            update_share_stats.assert_called_with(data)
 
     def _fake_safe_get(self, value):
         if value in ['emc_share_backend', 'share_backend_name']:

manila/tests/share/drivers/emc/test_emc_vnx.py

@@ -1201,7 +1201,7 @@ class EMCShareDriverVNXTestCase(test.TestCase):
         ]
         helper.XMLAPIConnector.request.assert_has_calls(expected_calls)
         helper.XMLAPIConnector.do_setup.assert_called_once_with()
-        pool_id = self.driver._storage_conn._pool['id']
+        pool_id = self.driver.plugin._pool['id']
         self.assertEqual(pool_id, TD.storage_pool_id_default,
                          "Storage pool id parse error")
 

setup.cfg

@@ -52,6 +52,8 @@ oslo.messaging.notify.drivers =
     manila.openstack.common.notifier.test_notifier = oslo.messaging.notify._impl_test:TestDriver
 oslo.config.opts =
     manila = manila.opts:list_opts
+manila.share.drivers.emc.plugins =
+    vnx = manila.share.drivers.emc.plugins.vnx.connection:VNXStorageConnection
 
 [build_sphinx]
 all_files = 1