Ignore syslog settings if /dev/log is not present

When journald crashes, the /dev/log socket is not present
and rootwrap calls fail with an unclear error message.

Ignore syslog configuration, log a warning and proceed in
those cases.

Change-Id: I4152593696ad63a977f127da3b00934feb14b069
Closes-Bug: #1730949

oslo_rootwrap/wrapper.py

@@ -99,10 +99,17 @@ class RootwrapConfig(object):
 
 
 def setup_syslog(execname, facility, level):
+    try:
+        handler = logging.handlers.SysLogHandler(address='/dev/log',
+                                                 facility=facility)
+    except IOError:
+        logging.warning("Unable to setup syslog, maybe /dev/log socket needs "
+                        "to be restarted. Ignoring syslog configuration "
+                        "options.")
+        return
+
     rootwrap_logger = logging.getLogger()
     rootwrap_logger.setLevel(level)
-    handler = logging.handlers.SysLogHandler(address='/dev/log',
-                                             facility=facility)
     handler.setFormatter(logging.Formatter(
                          os.path.basename(execname) + ': %(message)s'))
     rootwrap_logger.addHandler(handler)