Implement L3 Agent Extension Manager

Using the generalized agent extension mechanism, create an agent extension
manager in the L3 agent, so that the L3 agent can load agent extensions.

Co-Authored-By: Margaret Frances <margaret_frances@cable.comcast.com>
Implements: blueprint l3-agent-extensions
Needed-By: Iff506bd11b83d396305e631f3dd95d44cf38fd63

Change-Id: I6da92cb8b9fcbb603e120eababcf4ce711da3e30

neutron/agent/l3/agent.py

@@ -32,6 +32,7 @@ from neutron.agent.l3 import dvr_edge_router as dvr_router
 from neutron.agent.l3 import dvr_local_router as dvr_local_router
 from neutron.agent.l3 import ha
 from neutron.agent.l3 import ha_router
+from neutron.agent.l3 import l3_agent_extensions_manager as l3_ext_manager
 from neutron.agent.l3 import legacy_router
 from neutron.agent.l3 import namespace_manager
 from neutron.agent.l3 import namespaces
@@ -223,6 +224,8 @@ class L3NATAgent(ha.AgentMixin,
                     continue
             break
 
+        self.init_extension_manager(self.plugin_rpc)
+
         self.metadata_driver = None
         if self.conf.enable_metadata_proxy:
             self.metadata_driver = metadata_driver.MetadataDriver(self)
@@ -341,6 +344,7 @@ class L3NATAgent(ha.AgentMixin,
 
         try:
             self._router_removed(router_id)
+            self.l3_ext_manager.delete_router(self.context, router_id)
         except Exception:
             LOG.exception(_LE('Error while deleting router %s'), router_id)
             return False
@@ -363,6 +367,13 @@ class L3NATAgent(ha.AgentMixin,
 
         registry.notify(resources.ROUTER, events.AFTER_DELETE, self, router=ri)
 
+    def init_extension_manager(self, connection):
+        l3_ext_manager.register_opts(self.conf)
+        self.l3_ext_manager = (
+            l3_ext_manager.L3AgentExtensionsManager(self.conf))
+        self.l3_ext_manager.initialize(
+            connection, l3_constants.L3_AGENT_MODE)
+
     def router_deleted(self, context, router_id):
         """Deal with router deletion RPC message."""
         LOG.debug('Got router deleted notification for %s', router_id)
@@ -426,6 +437,7 @@ class L3NATAgent(ha.AgentMixin,
         ri.router = router
         ri.process(self)
         registry.notify(resources.ROUTER, events.AFTER_CREATE, self, router=ri)
+        self.l3_ext_manager.add_router(self.context, router)
 
     def _process_updated_router(self, router):
         ri = self.router_info[router['id']]
@@ -434,6 +446,7 @@ class L3NATAgent(ha.AgentMixin,
                         self, router=ri)
         ri.process(self)
         registry.notify(resources.ROUTER, events.AFTER_UPDATE, self, router=ri)
+        self.l3_ext_manager.update_router(self.context, router)
 
     def _resync_router(self, router_update,
                        priority=queue.PRIORITY_SYNC_ROUTERS_TASK):

neutron/agent/l3/l3_agent_extension.py

@@ -0,0 +1,55 @@
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import abc
+
+import six
+
+from neutron.agent import agent_extension
+
+
+@six.add_metaclass(abc.ABCMeta)
+class L3AgentCoreResourceExtension(agent_extension.AgentCoreResourceExtension):
+    """Define stable abstract interface for l3 agent extensions.
+
+    An agent extension extends the agent core functionality.
+    """
+
+    @abc.abstractmethod
+    def add_router(self, context, data):
+        """add agent extension for router.
+
+        Called on router create.
+
+        :param context: rpc context
+        :param data: router data
+        """
+
+    @abc.abstractmethod
+    def update_router(self, context, data):
+        """Handle agent extension for update.
+
+        Called on router update.
+
+        :param context: rpc context
+        :param data: router data
+        """
+
+    @abc.abstractmethod
+    def delete_router(self, context, data):
+        """Delete router from agent extension.
+
+        :param context: rpc context
+        :param data: router data
+        """

neutron/agent/l3/l3_agent_extensions_manager.py

@@ -0,0 +1,72 @@
+# Copyright (c) 2015 Mellanox Technologies, Ltd
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslo_log import log
+
+from neutron._i18n import _LE
+from neutron.agent import agent_extensions_manager as agent_ext_manager
+
+LOG = log.getLogger(__name__)
+
+
+L3_AGENT_EXT_MANAGER_NAMESPACE = 'neutron.agent.l3.extensions'
+
+
+def register_opts(conf):
+    agent_ext_manager.register_opts(conf)
+
+
+class L3AgentExtensionsManager(agent_ext_manager.AgentExtensionsManager):
+    """Manage l3 agent extensions."""
+
+    def __init__(self, conf):
+        super(L3AgentExtensionsManager, self).__init__(conf,
+                L3_AGENT_EXT_MANAGER_NAMESPACE)
+
+    def add_router(self, context, data):
+        """Notify all agent extensions to add router."""
+        for extension in self:
+            if hasattr(self, 'add_router'):
+                extension.obj.add_router(context, data)
+            else:
+                LOG.error(
+                    _LE("Agent Extension '%(name)s' does not "
+                        "implement method add_router"),
+                    {'name': extension.name}
+                )
+
+    def update_router(self, context, data):
+        """Notify all agent extensions to update router."""
+        for extension in self:
+            if hasattr(self, 'update_router'):
+                extension.obj.update_router(context, data)
+            else:
+                LOG.error(
+                    _LE("Agent Extension '%(name)s' does not "
+                        "implement method update_router"),
+                    {'name': extension.name}
+                )
+
+    def delete_router(self, context, data):
+        """Notify all agent extensions to delete router."""
+        for extension in self:
+            if hasattr(self, 'delete_router'):
+                extension.obj.delete_router(context, data)
+            else:
+                LOG.error(
+                    _LE("Agent Extension '%(name)s' does not "
+                        "implement method delete_router"),
+                    {'name': extension.name}
+                )

releasenotes/notes/l3-agent-extensions-b348ff26aec0fe88.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - The neutron L3 agent now has the ability to load
+    agent extensions, which allows other services to
+    integrate without additional agent changes.