Monitoring Tomcat via JMX–Lessons Learned: Part 2

In my previous post I mentioned that the check_jmx plugin I’ve used for monitoring JMX does not output perfdata data, which is useful for programs such as Centreon and Nagios which use this data to graph the output of the plugin.

The developers have made an excellent job with this plugin, and I hope they take the below script and incorporate into their official script Smile

I’ve written an “add-on” script which basically wraps around the official script and outputs the data in a perfdata friendly way, while keeping the nagios plugin OK/WARNING/CRITICAL states. The script isn’t perfect in the sense it could do with some input validation and a more helpful help, but it does work Smile

Below are the contents of the script “check_jmx_perfdata”, and assumes the plugin is located at /usr/local/nagios/libexec/check_jmx:
#!/bin/sh
# IMPORTANT, do not forget the ” ” when using this command as per example below
# example usage:
# ./check_jmx_perfdata “-U service:jmx:rmi:///jndi/rmi://localhost:9003/jmxrmi –O #Catalina:type=ThreadPool,name=http-8080 -A currentThreadCount”

# grab the original output from the check_jmx plugin

plugin_output=$(/usr/local/nagios/libexec/check_jmx $1)

# set the variables, where metric = attribute being monitored

# value = numeric value of the attribute

# result = OK/WARNING/CRITICAL/UNKNOWN state

metric=$(echo $plugin_output | cut -d ” ” -f 4)
value=$(echo $plugin_output | cut -d ” ” -f 6)
result=$(echo $plugin_output | cut -d ” ” -f 2)

# output the result with the added perfdata output
echo “$plugin_output | $metric=$value”


case “$result” in

OK)

exit 0
; ;

WARNING)

exit 1
;  ;

CRITICAL)

exit 2
; ;

UNKNOWN)

exit 3

esac


Instead of calling the check_jmx script from nagios, you will call the above script, using the exact same syntax but using the inverted commas. So for exmaple if you used:

check_jmx -U service:jmx:rmi:///jndi/rmi://localhost:9003/jmxrmi -O Catalina:type=Manager,path=/servlets-examples,host=localhost -A activeSessions

You’d now use:

check_jmx_perfdata “-U service:jmx:rmi:///jndi/rmi://localhost:9003/jmxrmi -O Catalina:type=Manager,path=/servlets-examples,host=localhost -A activeSessions”

Enjoy! Smile