Statgraph is a simple tool for graphing usage statistic from a number of unix hosts.

Statgraph makes use of the statgrab tool from http://www.i-scream.org/libstatgrab/ and has been tested on Linux, Solaris and FreeBSD. In theory, any platform supported by libstatgrab should work.

To make use of statgraph, you'll need perl and RRDtool, along with the perl bindings for RRDtool. On debian, these are included in the 'librrds-perl' package.

To collect statistics from a host, it will need the statgrab tool installed from libstatgrab. On a debian/ubuntu system, you can simply 'apt-get install statgrab'.

You'll need to decide how to collect statistics - either via a direct TCP connection to the target host, or by executing a command of your choice. This does mean you can make use of ssh with an ssh key if you want to keep open ports to a minimum.

If you're collecting via TCP, the easiest way to set things up is to run statgrab from inetd.

In /etc/services, add:

statgrab        27001/tcp

and in /etc/inetd.conf:

statgrab stream tcp nowait root /usr/sbin/tcpd /usr/bin/statgrab

You don't have to run it as root, but there are some statistics that it doesn't collect as an unprivileged user. The risk is relatively low as statgrab doesn't accept any input, and will simply print the statistics and exit, but there is always a risk with exposing a service. As always, you should seriously consider firewalling access to this port to trusted hosts only.

This has a bit more overhead, but does mean minimal changes to the server you're connecting to. Any command that generates statgrab output is fine. The simplest option is something like:

ssh -i ssh_key user@hostname /usr/bin/statgrab

The configuration for statgraph is statgraph.conf - this should be fairly self-explanatory, and a few examples are provided in statgraph.conf.example

To check it's all working, run ./statgraph.pl manually. If that looks good, add to cron and run once per minute. It will email you if a connection to a host fails though, so you might want to redirect output to a log file. I don't, since it's useful to know if a host is broken :)

To generate graphs, run the ./mkgraph.pl script. I run this every 10 minutes from cron, and it generates static html and .png images in whatever you've configured the graphs to live. By default this is the 'graphs' directory inside the statgraph directory.

This directory can be shared by a webserver and contains no dynamic code whatsoever.

• Statgraph is insanely spammy if a host is down, unless you redirect output

• Mounts with : in the name (remote NFS mounts for example) don't show up correctly.

• There's no sanity checking for return values, since they could massively vary. When I wrote statgraph the idea of 128 core machines was unimaginable, but we're there now, so I'm reluctant to hard code any values in. Occasionally a wonky value will make the graph scale a bit silly. There's a tool called 'rrdtrim' that can fix these. On an installation monitoring about 40 hosts, I probably have to fix 2 a year.

• Running it from cron can be a bit braindead sometime, and the timeouts could be more effective - occasionally processes do get wedged if the child does, but it's rare.

Statgraph is released under the GPLv2 license. See the COPYING file for details.