Varnish Nagios Plugin

Install

To use this plugin you need to have varnishstat installed which is installed by default when you install varnish.

Perl is also required for this plugin. If you don’t have Perl installed you can install in by running the command below
sudo apt-get install perl
or
sudo yum install perl

Now you can download the file above and extract it:
wget <a href="http://www.toms-blog.com/wp-content/uploads/2013/07/check_varnish-v1.0.tar.gz">http://www.toms-blog.com/wp-content/uploads/2013/07/check_varnish-v1.0.tar.gz</a>
tar -xzf check_varnish-v1.0.tar.gz

Now you should have a file “check_varnish.pl” make sure that it has execute permissions:
chmod u+x check_varnish.pl

You now need to copy this file to your nagios plugins folder. You should consult your nagios config to find out where this is. Mine was ‘/usr/lib/nagios/plugin’
1 mv check_varnish.pl /usr/lib/nagios/plugins/.
How To

check_varnish.pl – Monitor and report on varnish usage

check_varnish.pl [-c|–cache] [-b|–bin <varnishstatbinary>] [-d|–backend <total|ratio>] [-s|–stats <varnish statfield>] [-t|–technique <lt|gt>] [-w|–warning <number>] [-c|–critical <number>] [-h|–help]

DESCRIPTION

This script will report on various varnish stats including: varnish cache hit ratio backend error count (Total or Ratio) Any other counter in varnishstat If no counters are required the script will ensure the varnish binary is running

OPTIONS

-a –cache – this will make the script output cache_hit ratio perfdata

-b –bin <varnishstat> – to specify a different location of the default varnishstat binary location. Default is ‘/usr/bin/varnishstat’

-d –backend <all|success|unhealthy|busy|fail|reuse|toolate|recycle|retry> – specify script to output backend data you can output ratio, total or both

-h –help – output this message

-w –warning <number> – specify the warning threshold. Required for cache and backend checks

-c –critical <number> – specify the critical threshold. Required for cache and backend checks

-s –stats <varnishstat field> – specify a comma separated list of all the stats you wish to check Critical and Warning can be specified and all values will be compared to these values.

-t –technique <lt|gt> – when specifying stats you can also specify what technique you wish to use to compare the values to the thresholds. specify lt for less than and gt for greater than. Default is gt

EXAMPLES

Check varnish is running

./check_varnish.pl

Check varnish Cache Hit Ratio and warn if ratio is below 0.8

./check_varnish.pl -a -w 0.8 -c 0.6

Check varnish Backends

./check_varnish.pl -d all

Check varnish client requests and drops

./check_varnish.pl -s client_drop,client_req
Nagios Set Up

Once you have run the command in the CLI and all is working you can add the command:
1 define command {
2 command_name check_varnish
3 command_line $USER1$/check_varnish.pl $ARG1$
4 register 1
5 }

$USER1$ is your variable pointing to your nagios plugins folder and $ARG1$ are any command line arguments you specify in the service.
1 define service {
2 host_name localhost
3 service_description Varnish
4 check_command check_varnish!–cache -w 0.6 -c 0.4
5 register 1
6 }

The service above will give a warning if the hit ratio goes below 0.6 and critical if the ratio goes below 0.4
NRPE

The below is a line that can be used in the NRPE configuration for remote monitoring:
1 command[check_varnish_cache_hit]=/usr/lib/nagios/plugins/check_varnish.pl –cache -w 0.6 -c 0.4

The NRPE service could look like this:
1 define service {
2 host_name varnishserver
3 service_description Varnish Cache Hit Ratio
4 check_command check_nrpe!check_varnish_cache_hit
5 register 1
6 }

Download the plugin