I want to collect machine metrics and I want to display them as a pretty set of graphs through a web browser. Here’s how I do it:

  1. Install collectd — this gathers the metrics.
  2. Install lighttpd — my web server preference, also install php.
  3. Download and install collectd graph panel (CGP) — a PHP webapp.

That’s the short version.

Installation

The following walk through will demonstrate the installation using Ubuntu Oneiric (11.10). Note, the sudo is generally required, but dropped from the commands listed below:

apt-get install collectd lighttpd php5-cgi php5

next, edit /etc/php5/cgi/php.ini to enable php5 in lighttpd. Uncomment the line “cgi.fix_pathinfo=1“.

Restart lighttpd and you have a working lighttpd+php5.

lighttpd-enable-mod fastcgi
lighttpd-enable-mod fastcgi-php
service lighttpd force-reload

Next, download and “install” collectd graph panel (CGP). CGP is downloaded with git, if you do not have git installed then:

apt-get install git

Download CGP into the lighttpd root directory:

cd /var/www
git clone http://git.nethuis.nl/pub/cgp.git
chown -R www-data.www-data cgp   ## optional

Done! Browse to http://localhost/cgp/ to access the graphs.


Configuring what metrics collectd collects

The primary configuration for collectd as Ubuntu installs it is placed in /etc/collectd/collectd.conf. The configuration file is commented. Refer to the collectd documentation page for further details. For each plugin see the plugin pages listed along the side of the documentation page. Many plugins do not require additional configuration — simply uncommenting them is a good starting point.

After editing the collectd configuration, the service must be restarted with the typical service restart command:

service collectd restart

Many of the plugins default to collecting all possible metrics covered by the plugin. It is possible, via the plugin’s specific configuration, to prune out unwanted metrics. A good example of this is the ‘interfaces‘ plugin which includes statistics for the loopback interface by default.

Customizing CGP

The CGP website does not provide any configuration documentation, however it is not difficult to customize CGP. If installed, as shown above, CGP’s configuration file will be: /var/www/cgp/conf/config.php. This file is commented with details for changing the configuration.

Adding additional hosts

Nothing is required of CGP to add additional hosts. Simply install collectd on the additional machines and configure the network plugin on both the client and server. In most cases, the commented out configuration, which uses multicast, will suffice for configuring the network plugin.

Now sit back and enjoy the pretty graphs of your running servers.


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