Make OVSDB debug logging optional

OVSDB debug messages are very chatty and make log files much bigger
without a lot of benefit 99.9% of the time. If there is ever a need
for them because we are having a *really* weird OVSDB issue, then
we can configure the jobs to turn them back on.

Change-Id: I1d1e5e312509022084bcb651968bb9543ff61ba4
Closes-Bug: #1687065

neutron/agent/ovsdb/impl_idl.py

@@ -82,7 +82,8 @@ class OvsCleanup(command.BaseCommand):
 
 class NeutronOvsdbIdl(impl_idl.OvsdbIdl):
     def __init__(self, connection):
-        vlog.use_python_logger()
+        max_level = None if cfg.CONF.OVS.ovsdb_debug else vlog.INFO
+        vlog.use_python_logger(max_level=max_level)
         super(NeutronOvsdbIdl, self).__init__(connection)
 
     def ovs_cleanup(self, bridges, all_ports=False):

neutron/conf/agent/ovsdb_api.py

@@ -51,6 +51,9 @@ API_OPTS = [
                       'when interacting with OVSDB.  Required when using an '
                       '"ssl:" prefixed ovsdb_connection'
                       )),
+    cfg.BoolOpt('ovsdb_debug',
+                default=False,
+                help=_('Enable OVSDB debug logs')),
 ]