Skip to main content

syslog-ng statistics

For a long time I meant to give the "log statistics" feature of syslog-ng an overhaul, and finally with the advent of syslog-ng 3.0, this was done.

I'm not sure all of you know, but even earlier syslog-ng versions (2.1 and 2.0) did collect some per-source and per-destination statistics. These were reported periodically in the system log. The problem with this approach that it didn't really scale: with a large configuration the statistics message could become kilobytes long, and parsing this information from a file possibly several gigabytes in size is daunting.

syslog-ng 3.0 has two important changes in this area: it adds several new kinds of counters (like per-host counters), and a UNIX domain socket where you can query the current status of these counters.

As counters certainly have an overhead, you can now control how much statistics you want to gather. The new stats_level() option has three levels for now:
  1. stats_level(0) is basically the same as earlier syslog-ng versions, per-source and per-destination statistics are kept here. This is the default.
  2. stats_level(1) adds new counters without a big overhead, that is it adds counters for TCP connections, but does not keep per-host counters
  3. stats_level(2) adds counters that can have a measurable performance impact, it adds for example per-host (as in $HOST) counters and also keeps track of the time the last message was received from a given host. These counters usually require an hash table lookup in the fastpath.
Once you have the counters, you can still use the venerable "log statistics" message, by setting the stats_freq() option which defaults to 10 minutes, just like in earlier versions.

However if you don't want to dig the logs produced by syslog-ng, you can also use the new UNIX domain socket at /var/run/syslog-ng/syslog-ng.ctl (the path might depend on the compilation options).

If you connect to this socket using netcat (some netcat versions do support UNIX domain sockets), and you send a "STATS" command to it, you get the list of counters.

There are no proper, command line clients for the UNIX domain channel yet, but if you have some scripting ability, you can start gather statistics easily, without the hassles of parsing log files, right after installing a syslog-ng 3.0 snapshot. :)

Comments

Anonymous said…
Half of the sample log message is not visible - i guess it is not wrapped automatically.

Popular posts from this blog

syslog-ng fun with performance

I like christmas for a number of reasons: in addition to the traditional "meet and have fun with your family", eat lots of delicious food and so on, I like it because this is the season of the year when I have some time to do whatever I feel like. This year I felt like doing some syslog-ng performance analysis. After reading Ulrich Deppert's series about stuff "What every programmer should know about memory" on LWN, I thought I'm more than prepared to improve syslog-ng performance. Before going any further, I'd recommend this reading to any programmer, it's a bit long but every second reading it is worth it. As you need to measure performance in order to improve it, I wrote a tool called "loggen". This program generates messages messages at a user-specifyable rate. Apart from the git repository you can get this tool from the latest syslog-ng snapshots. Loggen supports TCP, UDP and UNIX domain sockets, so really almost everything can be me...

syslog-ng contributions redefined

syslog-ng has been around for about 12 years now, but I think the biggest change in the project's life is imminent: with the upcoming release of syslog-ng OSE 3.2, syslog-ng will become an independent entity. Until now, syslog-ng was primarily maintained & developed by BalaBit, copyrights needed to be reassigned in order to grant BalaBit special privileges. BalaBit used her privileges to create a dual-licensed fork of syslog-ng, named "syslog-ng Premium Edition". The value we offer over the Open Source Edition of syslog-ng are things that larger enterprises require: support on a large number of UNIX platforms (27 as of 3.1), smaller and larger feature differences (like the encrypted/digitally signed logfile feature) better test coverage and release management longer term support Although perfectly legal, this business model was not welcome in various Free Software communities, and has caused friction and harm, because BalaBit has enjoyed a privilege that no others cou...

An introduction to db-parser()

As promised on the mailing list here comes a short description of the new db-parser functionality of syslog-ng. For an introduction to parsers in general see my previous blog post here . The aim for db-parser is two-fold: extract interesting information from a log message attach tags to a log message for later classification. For instance here's a log sample (lines broken for readability): Feb 24 11:55:22 bzorp sshd[4376]: Accepted password for bazsi \ from 10.50.0.247 port 42156 ssh2 This message states that a user named "bazsi" has logged into the host named "bzorp" using SSH2 from the quoted IP and port. When you read this message as a human, the event that happened is perfectly clear. However if it is not a human, but a piece of software that has to make out the meaning of the message, you need to identify the event (e.g. that a user login has happened) and the additional information associated with the event (e.g. that he used 10.50.0.247 as the cl...