Moved CORS middleware configuration into oslo-config-generator

The default values needed for solum's implementation of cors
middleware have been moved from paste.ini into the configuration
hooks provided by oslo.config. Furthermore, these values have been
added to the default configuration parsing. This ensures
that if a value remains unset in solum.conf, it will be set
to use sane defaults, and that an operator modifying the
configuration file will be presented with a default set of
necessary sane headers.

Change-Id: I6f30224ac1b11fc4019dbc5ae5ec1e1fedbfe97d
Closes-Bug: 1551836

setup.cfg

@@ -81,5 +81,8 @@ oslo.config.opts =
     solum.deployer.handlers.heat = solum.deployer.handlers.heat:list_opts
     solum.worker.config = solum.worker.config:list_opts
 
+oslo.config.opts.defaults =
+    oslo.middleware.cors = solum.common.config:set_cors_middleware_defaults
+
 [wheel]
 universal = 1

solum/api/app.py

@@ -81,12 +81,5 @@ def setup_app(config=None):
     # Create a CORS wrapper, and attach solum-specific defaults that must be
     # supported on all CORS responses.
     app = cors_middleware.CORS(app, CONF)
-    app.set_latent(
-        allow_headers=['X-Auth-Token', 'X-Openstack-Request-Id',
-                       'X-Subject-Token'],
-        allow_methods=['GET', 'PUT', 'POST', 'DELETE', 'PATCH'],
-        expose_headers=['X-Auth-Token', 'X-Openstack-Request-Id',
-                        'X-Subject-Token']
-    )
 
     return app

solum/common/config.py

@@ -0,0 +1,41 @@
+# Copyright (c) 2016 Hewlett Packard Enterprise Development Corporation, LP
+#
+# 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_config import cfg
+from oslo_middleware import cors
+
+
+def set_config_defaults():
+    """This method updates all configuration default values."""
+    set_cors_middleware_defaults()
+
+
+def set_cors_middleware_defaults():
+    """Update default configuration options for oslo.middleware."""
+    # CORS Defaults
+    # TODO(krotscheck): Update with https://review.openstack.org/#/c/285368/
+    cfg.set_defaults(cors.CORS_OPTS,
+                     allow_headers=['X-Auth-Token',
+                                    'X-Openstack-Request-Id',
+                                    'X-Subject-Token'],
+                     expose_headers=['X-Auth-Token',
+                                     'X-Openstack-Request-Id',
+                                     'X-Subject-Token'],
+                     allow_methods=['GET',
+                                    'PUT',
+                                    'POST',
+                                    'DELETE',
+                                    'PATCH']
+                     )

solum/common/service.py

@@ -14,6 +14,7 @@
 
 from oslo_config import cfg
 
+from solum.common import config
 from solum import objects
 from solum.openstack.common import log as logging
 
@@ -21,4 +22,5 @@ from solum.openstack.common import log as logging
 def prepare_service(argv=[]):
     cfg.CONF(argv[1:], project='solum')
     logging.setup('solum')
+    config.set_config_defaults()
     objects.load()

solum/config.py

@@ -16,6 +16,7 @@
 
 from oslo_config import cfg
 
+from solum.common import config
 from solum import version
 
 
@@ -24,3 +25,4 @@ def parse_args(argv, default_config_files=None):
              project='solum',
              version=version.version_string(),
              default_config_files=default_config_files)
+    config.set_config_defaults()