Using syslog within python

Intro

We created a convention where-in our scripts log to syslog with a certain style. Originally these were Perl scripts but newer scripts are written in python. My question was, how to do in python what we had done in Perl?

The details

The linux system uses syslog-ng. In /etc/syslog-ng/conf.d I created a test file 03drj.conf with these contents:

destination d_drjtest { file("/var/log/drjtest.log"); };
filter f_drjtest{ program("drjtest"); };
log { source(s_src); filter(f_drjtest); destination(d_drjtest); flags(final); };

So we want that each of our little production scripts has its own log file in /var/log/.

The python test program I wrote which outputs to syslog is this:

[

import syslog
syslog.openlog('jhtest',syslog.LOG_PID,facility=syslog.LOG_LOCAL0)
syslog.syslog(syslog.LOG_NOTICE,'[Notice] Starting')
syslog.syslog(syslog.LOG_ERR,'[Error] We got an error')
syslog.syslog(syslog.LOG_INFO,'[Info] Just informational stuff')

Easy, right? Then someone newer to python showed me what he had done – not using syslog but logger, in which he accomplished pretty much the same goal but by different means. But he had to hard-code a lot more of the values and so it was not as elegant in my opinion.

In any case, the output is in /var/log/drjtest.log which look like this after a test run:

Jul 24 17:45:32 drjohnshost drjtest[928]: [Notice] Starting
Jul 24 17:45:32 drjohnshost drjtest[928]: [Error] We got an error
Jul 24 17:45:32 drjohnshost drjtest[928]: [Info] Just informational stuff

OSes using rsyslog

Today I needed to make this style of logging work on a new system which was running rsyslog. The OS is SLES v 15. For this OS I added a file to /etc/rsyslog.d called drjtest.conf with the contents:

if ($programname == 'drjtest' ) then {
        -/var/log/drjtest.log
        stop
}

But the python program did not need to change in any way.

Conclusion

We show how to properly use the syslog facility within python by using the syslog package. It’s all pretty obvious and barely needs to be mentioned, except when you’re just statring out you want a little hint that you may not find in the man pages or the documentation at syslog-ng.

References and related

I have a neat script which we use to parse all these other scripts and give us once a week summary emails, unless and error has been detected in which case the summary email goes out the day after a script has reported an error. It has some pretty nice logic if I say so myself. Here it is: drjohns script checker.