button-print-blu20 ZLB - Nagios Plugins Introduction

One of the deeper functions of Zen Load Balancer, is the ability to use the 3rd party Nagios tools for checking the viability of the target servers, by using the FarmGuardian options.

The tools are actually located in the following folder /usr/local/zenloadbalancer/app/libexec

The folder contains the following 5 scripts by default: check_http  check_ldap  check_smtp  check_tcp  check_uplink

For testing purposes, these command can be run from the server CLI by using: ./check_http -I -e 302 -s ‘Login.aspx’  -v

For example, in the above command line we are checking the HTTP status for a server at IP address, we expect to receive a HTTP status of 302 (not sure why but this is necessary with when using ZLB) and we want to see ‘Login.aspx’ as a string in the response.  The lower case -v, turn on verbose mode so that you can see the script run and the result. 

In order to select the correct ‘string’ simply run the command without the -s parameter, and view the HTTP response on screen.  Check that all the ‘real’ servers have a common response string and then re run the script.

When you finally paste the correct script into the Farm Guardian command window, substitute the IP address for HOST eg.  check_http -I HOST -e 302 -s ‘Login.aspx’

The Nagios script will then run in the background at the allocated interval for each ‘real’ server.

Hope this helps

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