Logging to syslog in Python
I was trying to use the standard Python
logging module to write messages to syslog. The
logging module has a
SysLogHandler class which can log to a local or remote syslog daemon.
With no host specified,
localhost which is what I wanted. I tried to use
SysLogHandler, but it just wouldn’t work. There was no error when I called the logging methods, but my messages didn’t show up in
syslog module works
Python also has a standard
syslog module. I tried it and it worked fine; my messages were written to the syslog file.
import syslog syslog.syslog('test')
syslogd isn’t listening
After running Wireshark I found the
SysLogHandler was correctly sending a UDP packet to
localhost on port 514. I could also see there was an ICMP response indicating the UDP packet was not received on that port. syslog wasn’t listening!
Instead of sending to
localhost, I wanted
SysLogHandler to pass the message to syslog on the local machine in the same way the
syslog Python module was doing.
The solution is to pass
/dev/log as the
address parameter to
SysLogHandler. It’s not well documented, but it works.
import logging from logging.handlers import SysLogHandler logger = logging.getLogger() logger.setLevel(logging.INFO) syslog = SysLogHandler(address='/dev/log') formatter = logging.Formatter('%(name)s: %(levelname)s %(message)s') syslog.setFormatter(formatter) logger.addHandler(syslog)
Easy when you know how.