I’ve been working with one of my coworkers in looking at Zabbix for monitoring rather than Nagios for the Global Ops Virtualization rollout. I’ve already done work on some monitoring of ESX3i with Nagios by writing some plugins to monitor different hardware components. (For more info see this blog post)
Zabbix supports multiple methods of checking on hosts/services with a preference for agents running on the monitored node. It also supports simple ping, http and ftp port type tests. There is also an option for what’s termed an “external check” which is more akin to how Nagios works.
We set up a VM running Ubuntu 7.10 and used apt-get to install Zabbix. This installed packages for version 1.4.1. (Version 1.4.5 is the most recent stable release.) In my testing I discovered that I wasn’t able to get external checks working. I kept getting an “agent not support” message when trying to set them up. In troubleshooting I downloaded the source and discovered a discrepancy between the what the front-end php (items.php) expects in the configuration when setting up an external check and what the c-code (zabbix-1.4.1./src/zabbix_server/poller/checks_external.c) was expecting to have submitted to it.
The documentation Zabbix provides says the following about external checks.
5.12.8. External checks
External check is a check executed by ZABBIX Server by running a shell script or a binary.
External checks do not require any agent running on a host being monitored.
Syntax of item’s key:
script(parameters)
script – name of the script.
parameters – list of command line parameters.
ZABBIX server will find and executed the script in directory defined in configuration parameter ExternalScripts. First command line parameter is host name, other parameters are substituted by parameters.
Note: Do not overuse external checks! It can decrease performance for ZABBIX system very much.
| Example 1: | Execute script check_oracle.sh with parameters “-h 192.168.1.4″. Host name ‘www1.company.com’. |
check_oracle.sh[-h 192.168.1.4]
ZABBIX will execute:
check_oracle.sh www1.company.com -h 192.168.1.4.
I noticed the server side piece was actually looking for parens “(” rather than square brackets “[". I tried to use parens check_oracle.sh(-h 192.168.1.4) but the front end wouldn't accept them. I was able to modify the front-end php code so that it accepted the parentheses and it worked fine after that.
The zabbix frontend files are installed (on this particular vm) at /usr/share/zabbix. In /usr/share/zabbix/include/defines.inc.php (line 391) change the definition of ZBX_EREG_ITEM_KEY_FORMAT from:
define('ZBX_EREG_ITEM_KEY_FORMAT', '('.ZBX_EREG_INTERNAL_NAMES.'(\['.ZBX_EREG_PARAMS.'\]){0,1})’);
To
define(‘ZBX_EREG_ITEM_KEY_FORMAT’, ‘(‘.ZBX_EREG_INTERNAL_NAMES.’(\(‘.ZBX_EREG_PARAMS.’\)){0,1})’);
I don’t know yet if this has been fixed in newer releases or not.
Hy,
i have a more or less little problem with external checks.
i have just a small script that executes a pyhton script and stores the value in a variable and echo this variable.
but zabbix deactivates the script everytime and says the script returned nothing.
if a execute the script manually (also as zabbix user) it works fine. any idea what happens, would be glad if you can help me.
scritp:
#!/usr/bin/bash
var1=$(/usr/bin/python webio.py)
echo $var1
br
Daniel
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Better late than never. I find these issues are usually related to environment and path issues.
In your case, I would also specify the full path the webio.py and redirect all debug output to files and even output that zabbix should receive to a file as well. confirm it’s not creating output. You’ll find that crons and non interactive shells sometimes have headaches on scripts we find work fine in our terminal.
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