Allow nova and others to override some logging defaults

- In log.py, indicate that logging module allows tweaking
of just logging_context_format_string option
- In cfg.py, add a method that can alter the default given
the options and new default
- add testcases for log.set_defaults and cfg.set_defaults

Fixes LP #1083218

Change-Id: Iefdbce8505eb7a07f2b59d4ed7564b0146f1b0cd

2 files changed, 13 insertions, 0 deletions

diff --git a/openstack/common/cfg.py b/openstack/common/cfg.py
index 69f0de8..004b3e9 100644
--- a/openstack/common/cfg.py
+++ b/openstack/common/cfg.py
@@ -480,6 +480,13 @@ def _is_opt_registered(opts, opt):
         return False
 
 
+def set_defaults(opts, **kwargs):
+    for opt in opts:
+        if opt.dest in kwargs:
+            opt.default = kwargs[opt.dest]
+            break
+
+
 class Opt(object):
 
     """Base class for all configuration options.
diff --git a/openstack/common/log.py b/openstack/common/log.py
index 8469fe8..707a10a 100644
--- a/openstack/common/log.py
+++ b/openstack/common/log.py
@@ -289,6 +289,12 @@ def setup(product_name):
         _setup_logging_from_conf(product_name)
 
 
+def set_defaults(logging_context_format_string):
+    cfg.set_defaults(log_opts,
+                     logging_context_format_string=
+                     logging_context_format_string)
+
+
 def _find_facility_from_conf():
     facility_names = logging.handlers.SysLogHandler.facility_names
     facility = getattr(logging.handlers.SysLogHandler,