Mod Gearman Quickstart Guide

Posted on January 8th, 2011 by sven

This quickstart guide was written for Debian Lenny (5.0) but probably works with different Linux systems too.

Note	This guide installs Mod-Gearman from source. Use packages whenever possible and only do a source install when there are no packages.

This guide assumes you have a basic nagios system running.

All commands have to be executed as root.

Build Preparation

We need a couple of packages for building Gearman and Mod-Gearman:

#> apt-get update
#> apt-get install autoconf automake make gcc g++ wget tar file netcat uuid-dev libltdl3-dev libncurses5-dev libevent-dev

We will install Gearman in /opt to make later removal easier. For example if there will be a Debian package sometimes. This keeps your base system clean from non-packaged software, but in order to make that work, we have to add /opt/lib to the ld lib path.

#> echo "/opt/lib" > /etc/ld.so.conf.d/opt_lib.conf
#> ldconfig

Install Gearman

We need at least Gearman version >= 0.14. Execute the following steps to install Gearman from source.

#> cd /tmp
#> wget "http://launchpad.net/gearmand/trunk/0.25/+download/gearmand-0.25.tar.gz"
#> tar zxf gearmand-0.25.tar.gz
#> cd gearmand-0.25
#> ./configure --prefix=/opt
#> make
#> make install

Mod-Gearman

Half way done, the next step installs Mod-Gearman.

#> cd /tmp
#> wget "http://labs.consol.de/wp-content/uploads/2010/09/mod_gearman-1.4.2.tar.gz"
#> tar zxf mod_gearman-1.4.2.tar.gz
#> cd mod_gearman-1.4.2
#> ./configure --prefix=/opt --with-gearman=/opt --with-user=nagios --with-init-dir=/etc/init.d
#> make
#> make install
#> make install-config
#> cp ./extras/gearmand-init /etc/init.d/gearmand

Nagios

We need a nagios installation if not already installed.

#> apt-get install nagios3

Gearman runs as user nagios which needs a valid shell:

#> chsh nagios
Changing the login shell for nagios
Enter the new value, or press ENTER for the default
        Login Shell [/bin/false]: /bin/bash

Starting Up

Now we can start the Gearman daemon and our Mod-Gearman worker:

#> /etc/init.d/gearmand start
Starting gearmand done
#> /etc/init.d/gearmand status
gearmand is running with pid 31869
#> /etc/init.d/mod_gearman_worker start
Starting mod_gm_worker done
#> /etc/init.d/mod_gearman_worker status
mod_gm_worker is running with pid 31939

Nagios Configuration

Open your nagios.cfg and enable eventbroker. When using the packaged nagios3 from Debian the file is located at /etc/nagios3/nagios.cfg.

event_broker_options=-1
broker_module=/opt/lib/mod_gearman/mod_gearman.o config=/opt/etc/mod_gearman.conf

and finally restart nagios:

#> /etc/init.d/nagios3 restart
Restarting nagios3 monitoring daemon: nagios3

Your nagios.log should contain a line:

#> grep mod_gearman /var/log/nagios3/nagios.log
[1295003042] mod_gearman: Version 1.4.2
[1295003042] Event broker module '/opt/lib/mod_gearman/mod_gearman.o' initialized successfully.

Testing

We can perform a few tests to see if everything is up and running.

Gearman-Top

First we have a look at /opt/bin/gearman_top. You should have at least one worker for each queue.

2011-01-07 23:23:24  -  localhost:4730   -  v0.25
Queue Name      | Worker Available | Jobs Waiting | Jobs Running
------------------------------------------------------------------
check_results   |               1  |           0  |           0
eventhandler    |               1  |           0  |           0
host            |               1  |           0  |           0
service         |               1  |           0  |           0
worker_debian64 |               1  |           0  |           0
------------------------------------------------------------------

Check-Gearman

Then we have a look at the shiped check plugin:

#> /opt/bin/check_gearman -H localhost -q worker_`hostname` -t 10 -s check
check_gearman OK - debian64 has 1 worker and is working on 0 jobs. Version: 1.4.2|worker=1 jobs=2c

The interesting number is the last one, 2c in our case, which means there have been already 2 jobs executed by this worker.

Troubleshooting

First check if everything is up and running:

 #> /etc/init.d/nagios3 status
 checking /usr/sbin/nagios3...done (running).
 #> /etc/init.d/gearmand status
 gearmand is running with pid 31921
 #> /etc/init.d/mod_gearman_worker status
 mod_gm_worker is running with pid 31939

If one of them is not running, try to start it or check the logfiles for possible error messages.

Nagios: /var/log/nagios3/nagios.log
Gearmand: /opt/var/mod_gearman/gearmand.log
Mod-Gearman Worker: /opt/var/mod_gearman/mod_gearman_worker.log

2 Responses to “Mod Gearman Quickstart Guide”

Neu in omd 0.48: mod_gearman und check_multi | KenntWas.de - Technische Tipps Says:
May 28th, 2011 at 16:24
[...] 0.48: Enable Mod_GearmanMod_gearman ist jetzt fest im OMD 0.48 integriert. Eine separate Installation ist nicht mehr nötig. Sven Nierlein hat auf dem Monitoring Workshop 2011 einen guten Vortrag über [...]
Integrating mod_gearman with Centreon / Nagios « Dvas0004's Blog Says:
February 27th, 2012 at 13:58
[...] http://labs.consol.de/lang/de/nagios/mod-gearman/mod-gearman-quickstart-guide/ [...]