Enable OSProfiler support in Ironic - follow-up

Fixes nits, updates documentation and releasenotes.

This is a follow-up to commit 3773f17403.

Change-Id: I4082bbb9f8c09eaf4569317eb1387bf9a36ef254
Partial-Bug: #1560704

doc/source/contributor/osprofiler-support.rst

@@ -70,6 +70,7 @@ profiler options and restart ironic services::
     [profiler]
     enabled = True
     hmac_keys = SECRET_KEY # default value used across several OpenStack projects
+    trace_sqlalchemy = True
 
 
 In order to trace ironic using OSProfiler, use openstackclient to run
@@ -95,6 +96,10 @@ The trace results can be saved in a file with ``--out file-name`` option::
 
     $ osprofiler trace show --html <trace-id> --out trace.html
 
+The trace results show the time spent in ironic-api, ironic-conductor, and db
+calls. More detailed db tracing is enabled if ``trace_sqlalchemy``
+is set to true.
+
 Sample Trace:
 
 .. figure:: ../images/sample_trace.svg
@@ -103,6 +108,8 @@ Sample Trace:
    :alt: Sample Trace
 
 
+Each trace has embedded trace point details as shown below:
+
 .. figure:: ../images/sample_trace_details.svg
    :width: 660px
    :align: left

ironic/common/profiler.py

@@ -32,16 +32,18 @@ def setup(name, host='0.0.0.0'):
                        a notifier backend, which is set in
                        osprofiler.initializer.init_from_conf.
     """
-    if CONF.profiler.enabled:
-        admin_context = context.get_admin_context()
-        initializer.init_from_conf(conf=CONF,
-                                   context=admin_context.to_dict(),
-                                   project="ironic",
-                                   service=name,
-                                   host=host)
-        LOG.info("OSProfiler is enabled. Trace is generated using "
-                 "[profiler]/hmac_keys specified in ironic.conf. "
-                 "To disable, set [profiler]/enabled=false")
+    if not CONF.profiler.enabled:
+        return
+
+    admin_context = context.get_admin_context()
+    initializer.init_from_conf(conf=CONF,
+                               context=admin_context.to_dict(),
+                               project="ironic",
+                               service=name,
+                               host=host)
+    LOG.info("OSProfiler is enabled. Trace is generated using "
+             "[profiler]/hmac_keys specified in ironic.conf. "
+             "To disable, set [profiler]/enabled=false")
 
 
 def trace_cls(name, **kwargs):
@@ -54,7 +56,7 @@ def trace_cls(name, **kwargs):
     :param kwargs: Any other keyword args used by profiler.trace_cls
     """
     def decorator(cls):
-        if profiler and 'profiler' in CONF and CONF.profiler.enabled:
+        if CONF.profiler.enabled:
             trace_decorator = profiler.trace_cls(name, kwargs)
             return trace_decorator(cls)
         return cls