Fix syslog module usage breaking Windows compatibility

The following change removed the platform check that was preventing
the syslog handler class from being defined on incompatible
platforms: d61af05ff10e92e73ec8745be5f1828e6b2effda

The only issue with that is the fact that one method default value
uses a syslog module constant that gets evaluated even if the class
itself is never instantiated.

This patch fixes the issue by moving that default value within the
init method.

Closes-Bug: #1682177

Change-Id: Ie88e367957c5739f335cb96fcefc8501a9bf4bcd

1 files changed, 4 insertions, 1 deletions

diff --git a/oslo_log/handlers.py b/oslo_log/handlers.py
index 852d4bf..8e561a4 100644
--- a/oslo_log/handlers.py
+++ b/oslo_log/handlers.py
@@ -56,7 +56,10 @@ SYSLOG_MAP = {
 class OSSysLogHandler(logging.Handler):
     """Syslog based handler. Only available on UNIX-like platforms."""
 
-    def __init__(self, facility=syslog.LOG_USER):
+    def __init__(self, facility=None):
+        # Default values always get evaluated, for which reason we avoid
+        # using 'syslog' directly, which may not be available.
+        facility = facility if facility is not None else syslog.LOG_USER
         # Do not use super() unless type(logging.Handler) is 'type'
         # (i.e. >= Python 2.7).
         if not syslog: