From dfb4e68e005e68a2e272f92c62fc8455712f293a Mon Sep 17 00:00:00 2001
From: Aditi Raveesh <aditirav@thoughtworks.com>
Date: Tue, 14 May 2013 15:33:14 +0530
Subject: Add Middleware for correlation_id

The middleware generates the 'correlation_id' if it is not already present
in the request header. This 'correlation_id' can be used to enable more
effective debugging of requests that span multiple services.

Implements: blueprint create-a-unified-correlation-id

Change-Id: Ibc06a5b05b628e0b640e9299c79127ecbf9c684e
---
 openstack/common/middleware/correlation_id.py | 29 +++++++++++++++++++++++++++
 openstack/common/wsgi.py                      | 11 ++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 openstack/common/middleware/correlation_id.py

(limited to 'openstack')

diff --git a/openstack/common/middleware/correlation_id.py b/openstack/common/middleware/correlation_id.py
new file mode 100644
index 0000000..a3efe34
--- /dev/null
+++ b/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 openstack.common import uuidutils
+from openstack.common 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
diff --git a/openstack/common/wsgi.py b/openstack/common/wsgi.py
index d184963..80d4b9b 100644
--- a/openstack/common/wsgi.py
+++ b/openstack/common/wsgi.py
@@ -172,6 +172,17 @@ class Middleware(object):
     behavior.
     """
 
+    @classmethod
+    def factory(cls, global_conf, **local_conf):
+        """
+        Factory method for paste.deploy
+        """
+
+        def filter(app):
+            return cls(app)
+
+        return filter
+
     def __init__(self, application):
         self.application = application
 
-- 
cgit