How to configure logging to syslog in Python?

Question

Change the line to this:

handler = SysLogHandler(address='/dev/log')

This works for me

import logging
import logging.handlers

my_logger = logging.getLogger('MyLogger')
my_logger.setLevel(logging.DEBUG)

handler = logging.handlers.SysLogHandler(address = '/dev/log')

my_logger.addHandler(handler)

my_logger.debug('this is debug')
my_logger.critical('this is critical')

You should always use the local host for logging, whether to /dev/log or localhost through the TCP stack. This allows the fully RFC compliant and featureful system logging daemon to handle syslog. This eliminates the need for the remote daemon to be functional and provides the enhanced capabilities of syslog daemon's such as rsyslog and syslog-ng for instance. The same philosophy goes for SMTP. Just hand it to the local SMTP software. In this case use 'program mode' not the daemon, but it's the same idea. Let the more capable software handle it. Retrying, queuing, local spooling, using TCP instead of UDP for syslog and so forth become possible. You can also [re-]configure those daemons separately from your code as it should be.

Save your coding for your application, let other software do it's job in concert.

I found the syslog module to make it quite easy to get the basic logging behavior you describe:

import syslog
syslog.syslog("This is a test message")
syslog.syslog(syslog.LOG_INFO, "Test message at INFO priority")

There are other things you could do, too, but even just the first two lines of that will get you what you've asked for as I understand it.

Piecing things together from here and other places, this is what I came up with that works on unbuntu 12.04 and centOS6

Create an file in /etc/rsyslog.d/ that ends in .conf and add the following text

local6.*        /var/log/my-logfile

Restart rsyslog, reloading did NOT seem to work for the new log files. Maybe it only reloads existing conf files?

sudo restart rsyslog

Then you can use this test program to make sure it actually works.

import logging, sys
from logging import config

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'verbose': {
            'format': '%(levelname)s %(module)s P%(process)d T%(thread)d %(message)s'
            },
        },
    'handlers': {
        'stdout': {
            'class': 'logging.StreamHandler',
            'stream': sys.stdout,
            'formatter': 'verbose',
            },
        'sys-logger6': {
            'class': 'logging.handlers.SysLogHandler',
            'address': '/dev/log',
            'facility': "local6",
            'formatter': 'verbose',
            },
        },
    'loggers': {
        'my-logger': {
            'handlers': ['sys-logger6','stdout'],
            'level': logging.DEBUG,
            'propagate': True,
            },
        }
    }

config.dictConfig(LOGGING)


logger = logging.getLogger("my-logger")

logger.debug("Debug")
logger.info("Info")
logger.warn("Warn")
logger.error("Error")
logger.critical("Critical")

I add a little extra comment just in case it helps anyone because I found this exchange useful but needed this little extra bit of info to get it all working.

To log to a specific facility using SysLogHandler you need to specify the facility value. Say for example that you have defined:

local3.* /var/log/mylog

in syslog, then you'll want to use:

handler = logging.handlers.SysLogHandler(address = ('localhost',514), facility=19)

and you also need to have syslog listening on UDP to use localhost instead of /dev/log.

Is your syslog.conf set up to handle facility=user?

You can set the facility used by the python logger with the facility argument, something like this:

handler = logging.handlers.SysLogHandler(facility=SysLogHandler.LOG_DAEMON)