[placement] Use own set_middleware_defaults

The CORS middleware needs to have its defaults set to something
reaonable. Placement had been using some code in nova to do so.
This change duplicates that code into the placement WSGI app
which had been calling it.

Change-Id: I025a2d14c4126f68e199efa54329797576c50677
blueprint: placement-extract

nova/api/openstack/placement/wsgi.py

@@ -19,12 +19,12 @@ import os
 import os.path
 
 from oslo_log import log as logging
+from oslo_middleware import cors
 from oslo_utils import importutils
 import pbr.version
 
 from nova.api.openstack.placement import db_api
 from nova.api.openstack.placement import deploy
-from nova.common import config
 from nova import conf
 
 
@@ -63,12 +63,34 @@ def _parse_args(argv, default_config_files):
     if profiler:
         profiler.set_defaults(conf.CONF)
 
-    config.set_middleware_defaults()
+    _set_middleware_defaults()
 
     conf.CONF(argv[1:], project='nova', version=version_info.version_string(),
               default_config_files=default_config_files)
 
 
+def _set_middleware_defaults():
+    """Update default configuration options for oslo.middleware."""
+    cors.set_defaults(
+        allow_headers=['X-Auth-Token',
+                       'X-Openstack-Request-Id',
+                       'X-Identity-Status',
+                       'X-Roles',
+                       'X-Service-Catalog',
+                       'X-User-Id',
+                       'X-Tenant-Id'],
+        expose_headers=['X-Auth-Token',
+                        'X-Openstack-Request-Id',
+                        'X-Subject-Token',
+                        'X-Service-Token'],
+        allow_methods=['GET',
+                       'PUT',
+                       'POST',
+                       'DELETE',
+                       'PATCH']
+    )
+
+
 def init_application():
     # initialize the config system
     conffile = _get_config_file()