Add RPC server code

Magnum will end up with several RPC servers to execute the various
RPC operations.  This is copied from Solum.

Change-Id: Ie2ba81c19e7a304e2e92c9bdc6db898de8a45922

magnum/common/rpc/service.py

@@ -0,0 +1,107 @@
+# Copyright 2014 - Rackspace Hosting
+#
+#    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.
+
+"""Common RPC service and API tools for Magnum."""
+
+import eventlet
+from oslo.config import cfg
+from oslo import messaging
+from oslo.serialization import jsonutils
+
+import magnum.common.context
+
+
+# NOTE(paulczar):
+# Ubuntu 14.04 forces librabbitmq when kombu is used
+# Unfortunately it forces a version that has a crash
+# bug.  Calling eventlet.monkey_patch() tells kombu
+# to use libamqp instead.
+eventlet.monkey_patch()
+
+# NOTE(asalkeld):
+# The magnum.openstack.common.rpc entries are for compatability
+# with devstack rpc_backend configuration values.
+TRANSPORT_ALIASES = {
+    'magnum.openstack.common.rpc.impl_kombu': 'rabbit',
+    'magnum.openstack.common.rpc.impl_qpid': 'qpid',
+    'magnum.openstack.common.rpc.impl_zmq': 'zmq',
+}
+
+
+class JsonPayloadSerializer(messaging.NoOpSerializer):
+    @staticmethod
+    def serialize_entity(context, entity):
+        return jsonutils.to_primitive(entity, convert_instances=True)
+
+
+class RequestContextSerializer(messaging.Serializer):
+
+    def __init__(self, base=None):
+        self._base = base or messaging.NoOpSerializer()
+
+    def serialize_entity(self, context, entity):
+        if not self._base:
+            return entity
+        return self._base.serialize_entity(context, entity)
+
+    def deserialize_entity(self, context, entity):
+        if not self._base:
+            return entity
+        return self._base.deserialize_entity(context, entity)
+
+    def serialize_context(self, context):
+        return context.to_dict()
+
+    def deserialize_context(self, context):
+        return magnum.common.context.RequestContext.from_dict(context)
+
+
+class Service(object):
+    _server = None
+
+    def __init__(self, topic, server, handlers):
+        serializer = RequestContextSerializer(JsonPayloadSerializer())
+        transport = messaging.get_transport(cfg.CONF,
+                                            aliases=TRANSPORT_ALIASES)
+        # TODO(asalkeld) add support for version='x.y'
+        target = messaging.Target(topic=topic, server=server)
+        self._server = messaging.get_rpc_server(transport, target, handlers,
+                                                serializer=serializer)
+
+    def serve(self):
+        self._server.start()
+        self._server.wait()
+
+
+class API(object):
+    def __init__(self, transport=None, context=None, topic=None):
+        serializer = RequestContextSerializer(JsonPayloadSerializer())
+        if transport is None:
+            transport = messaging.get_transport(cfg.CONF,
+                                                aliases=TRANSPORT_ALIASES)
+        self._context = context
+        if topic is None:
+            topic = ''
+        target = messaging.Target(topic=topic)
+        self._client = messaging.RPCClient(transport, target,
+                                           serializer=serializer)
+
+    def _call(self, method, *args, **kwargs):
+        return self._client.call(self._context, method, *args, **kwargs)
+
+    def _cast(self, method, *args, **kwargs):
+        self._client.cast(self._context, method, *args, **kwargs)
+
+    def echo(self, message):
+        self._cast('echo', message=message)

requirements.txt

@@ -6,6 +6,8 @@ pbr>=0.6,!=0.7,<1.0
 Babel>=1.3
 
 oslo.config>=1.4.0
+oslo.messaging>=1.4.0
+oslo.serialization>=1.0.0
 oslo.utils>=1.0.0
 pecan>=0.8.0
 python-keystoneclient>=0.11.1