old_contents: #    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 neutron_lib import constants as cons
  from oslo_log import log as logging
  from oslo_middleware import base
  import webob
  
  LOG = logging.getLogger(__name__)
  
  
  class RequestSource(base.ConfigurableMiddleware):
      """RequestSource Middleware
  
      This middleware distinguishes the source of the requests. It can find out
      which request is from central Neutron and which is from local Neutron.
  
      This middleware updates the context to put the source of requests
      extracted from headers.
  
      In order to make RequestSource Middleware work, this middleware should
      place after keystoneContext(in etc/neutron/api-paste.ini).
      """
  
      def distinguish_requests_source(self, req):
          source_header = req.headers.get(cons.USER_AGENT, "")
  
          if source_header in cons.REQUEST_SOURCE_TYPE:
              ctx = req.environ['neutron.context']
              ctx.USER_AGENT = source_header
              req.environ['neutron.context'] = ctx
  
      @webob.dec.wsgify
      def __call__(self, req):
          self.distinguish_requests_source(req)
  
          response = req.get_response(self.application)
          return response
  
new_contents: #    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 as logging
  from oslo_middleware import base
  from tricircle.common import constants as cons
  import webob
  
  LOG = logging.getLogger(__name__)
  
  
  class RequestSource(base.ConfigurableMiddleware):
      """RequestSource Middleware
  
      This middleware distinguishes the source of the requests. It can find out
      which request is from central Neutron and which is from local Neutron.
  
      This middleware updates the context to put the source of requests
      extracted from headers.
  
      In order to make RequestSource Middleware work, this middleware should
      place after keystoneContext(in etc/neutron/api-paste.ini).
      """
  
      def distinguish_requests_source(self, req):
          source_header = req.headers.get(cons.USER_AGENT, "")
  
          if source_header in cons.REQUEST_SOURCE_TYPE:
              ctx = req.environ['neutron.context']
              ctx.USER_AGENT = source_header
              req.environ['neutron.context'] = ctx
  
      @webob.dec.wsgify
      def __call__(self, req):
          self.distinguish_requests_source(req)
  
          response = req.get_response(self.application)
          return response
  
subject: Fix Tricircle Constants module could not be imported refer to https://bugs.launchpad.net/tricircle/+bug/1868777