Importing correlation_id middleware from oslo-incubator

Including 'correlation_id' middleware from oslo-incubator.
Adding this to openstack-common.conf to copy over the middleware to
the location nova/openstack/common/middleware

Change-Id: I21b27e8dae585345d03d59c125d9e1bbea95f830
Implements: blueprint cross-service-request-id

nova/openstack/common/middleware/correlation_id.py

@@ -0,0 +1,29 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2013 Rackspace Hosting
+# 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.
+
+"""Middleware that attaches a correlation id to WSGI request"""
+
+from nova.openstack.common import uuidutils
+from nova import wsgi
+
+
+class CorrelationIdMiddleware(wsgi.Middleware):
+
+    def process_request(self, req):
+        correlation_id = (req.headers.get("X_CORRELATION_ID") or
+                          uuidutils.generate_uuid())
+        req.headers['X_CORRELATION_ID'] = correlation_id

openstack-common.conf

@@ -18,6 +18,7 @@ module=lockutils
 module=log
 module=loopingcall
 module=memorycache
+module=middleware.correlation_id
 module=network_utils
 module=notifier
 module=patch_tox_venv