create placement API wsgi entry point

We want a wsgi_script as the entry point for our placement API
actually getting run, this is wrapping in the smooth and mellow pbr
patterns that make it sensible to also run just by starting it on the
command line.

This also actually initializes the logging subsystem for the placement
API, and does the standard pattern of dumping the configuration if
DEBUG is enabled. Pieces of this were cribbed/inspired by equivalent
keystone code.

The config directory is now setable via environment, which may be be
needed by folks with venvs.

Change-Id: I00d032554de273d7493cfb467f81687c08fd5389

nova/api/openstack/placement/wsgi.py

@@ -0,0 +1,65 @@
+#    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.
+"""WSGI script for Placement API
+
+WSGI handler for running Placement API under Apache2, nginx, gunicorn etc.
+"""
+
+import logging as py_logging
+import os
+import os.path
+
+from nova.api.openstack.placement import deploy
+from nova import conf
+from nova import config
+
+from oslo_log import log as logging
+
+CONFIG_FILE = 'nova.conf'
+
+
+def setup_logging(config):
+    # Any dependent libraries that have unhelp debug levels should be
+    # pinned to a higher default.
+    extra_log_level_defaults = [
+        'routes=INFO',
+    ]
+    logging.set_defaults(default_log_levels=logging.get_default_log_levels() +
+                    extra_log_level_defaults)
+    logging.setup(config, 'nova')
+    py_logging.captureWarnings(True)
+
+
+def _get_config_file(env=None):
+    if env is None:
+        env = os.environ
+
+    dirname = env.get('OS_PLACEMENT_CONFIG_DIR', '/etc/nova').strip()
+    return os.path.join(dirname, CONFIG_FILE)
+
+
+def init_application():
+    # initialize the config system
+    conffile = _get_config_file()
+    config.parse_args([], default_config_files=[conffile])
+
+    # initialize the logging system
+    setup_logging(conf.CONF)
+
+    # dump conf if we're at debug
+    if conf.CONF.debug:
+        conf.CONF.log_opt_values(
+            logging.getLogger(__name__),
+            logging.DEBUG)
+
+    # build our paste app and return it for wsgi goodness
+    return deploy.loadapp(conf.CONF)

setup.cfg

@@ -68,6 +68,8 @@ console_scripts =
     nova-serialproxy = nova.cmd.serialproxy:main
     nova-spicehtml5proxy = nova.cmd.spicehtml5proxy:main
     nova-xvpvncproxy = nova.cmd.xvpvncproxy:main
+wsgi_scripts =
+    nova-placement-api = nova.api.openstack.placement.wsgi:init_application
 
 nova.api.v21.extensions =
     admin_actions = nova.api.openstack.compute.admin_actions:AdminActions