Add support for osprofiler in wsgi

To use osprofiler with placement:

* Add a [profiler] section to the placement.conf (and other openstack
  service conf files):

  [profiler]
  connection_string = mysql+pymysql://root:admin@127.0.0.1/osprofiler?charset=utf8
  hmac_keys = my-secret-key
  trace_sqlalchemy = True
  enabled = True

* Include the hmac_keys in your API request

  $ openstack server create --flavor c1 --image cirros-0.4.0-x86_64-disk \
    --os-profile my-secret-key vm --wait

  The openstack client will return the trace id:

  Trace ID: 67428cdd-bfaa-496f-b430-507165729246
  $

* Extrace the trace in html format

  $ osprofiler trace show --html 67428cdd-bfaa-496f-b430-507165729246 \
    --connection-string mysql+pymysql://root:admin@127.0.0.1/osprofiler?charset=utf8

Here is an example trace output for the above server create request
including the placement interactions enabled by this patch:
https://pste.eu/p/ZFsb.html

Story: 2005842
Task: 33616

Change-Id: I5a0e805fe04c00c5e7cf316f0ea8d432b940e560

placement/deploy.py

@@ -15,6 +15,7 @@ import os
 
 from microversion_parse import middleware as mp_middleware
 import oslo_middleware
+from oslo_utils import importutils
 
 from placement import auth
 from placement.db.sqlalchemy import migration
@@ -30,6 +31,10 @@ from placement import resource_class_cache as rc_cache
 from placement import util
 
 
+os_profiler = importutils.try_import('osprofiler.profiler')
+os_profiler_web = importutils.try_import('osprofiler.web')
+
+
 PROFILER_OUTPUT = os.environ.get('OS_WSGI_PROFILER')
 if PROFILER_OUTPUT:
     # If werkzeug is not available this raises ImportError and the
@@ -63,6 +68,12 @@ def deploy(conf):
     fault_middleware = fault_wrap.FaultWrapper
     request_log = requestlog.RequestLog
 
+    if os_profiler_web and 'profiler' in conf and conf.profiler.enabled:
+        osprofiler_middleware = os_profiler_web.WsgiMiddleware.factory(
+            {}, **conf.profiler)
+    else:
+        osprofiler_middleware = None
+
     application = handler.PlacementHandler(config=conf)
 
     # If PROFILER_OUTPUT is set, generate per request profile reports
@@ -90,6 +101,7 @@ def deploy(conf):
                        auth_middleware,
                        cors_middleware,
                        req_id_middleware,
+                       osprofiler_middleware,
                        ):
         if middleware:
             application = middleware(application)

placement/wsgi.py

@@ -30,6 +30,8 @@ from placement import db_api
 from placement import deploy
 
 
+osprofiler = importutils.try_import('osprofiler')
+osprofiler_initializer = importutils.try_import('osprofiler.initializer')
 profiler = importutils.try_import('osprofiler.opts')
 
 
@@ -86,6 +88,16 @@ def _parse_args(config, argv, default_config_files):
            default_config_files=default_config_files)
 
 
+def setup_profiler(config):
+    if osprofiler and config.profiler.enabled:
+        osprofiler.initializer.init_from_conf(
+            conf=config,
+            context={},
+            project="placement",
+            service="placement",
+            host="??")
+
+
 def _set_middleware_defaults():
     """Update default configuration options for oslo.middleware."""
     cors.set_defaults(
@@ -134,5 +146,7 @@ def init_application():
             logging.getLogger(__name__),
             logging.DEBUG)
 
+    setup_profiler(config)
+
     # build and return our WSGI app
     return deploy.loadapp(config)

releasenotes/notes/fix-osprofiler-support-78b34a92c32fd30f.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    By fixing bug `story/2005842`_ the OSProfiler support works again in the
+    placement WSGI.
+
+    .. _story/2005842: https://storyboard.openstack.org/#!/story/2005842