Monday, 11 August 2008

Drawing graphs with graphite

Work continues a-pace ... well kinda. I've added a new reporting plugin for a new monitoring system: Graphite [see launch-pad and wiki sites]. If you've not heard, is a funky new monitoring system that does away with the traditional RRDTool and does everything in python.

There's two main components to Graphite: carbon and graphite.

Carbon is a recording daemon (in fact, a set of three daemons) that stores information efficiently on disk (using a custom format) and maintain a fast in-memory cache. Sending new metric values to the carbon agent is very simply.

Graphite is a python web front-end that uses the Django framework and the ExtJS AJAX toolkit. Graph rendering is achieved using cairo (via python's cairo bindings). It's possible to run Graphite (Django) in stand-alone mode, but I guess most people will use mod_python and apache. Although there's a simple drag-and-drop compositor, the real power comes when using the CLI interface. There, each logged-in user can create their own custom graphs (multiple can be opened concurrently). These can be arranged on the screen and the resulting view saved for later recall.

It's a bit of a faff to setup (although better with v0.9.3) and there's a few rough edges (again, better with v0.9.3). That said, it's already usable and the AJAX interface is pretty nice. It's early days, so I'm not sure where it will fit within the monitoring eco-system compared to established projects (e.g., ganglia, munin, cacti). I guess time will tell.

Because of the way Graphite (and Carbon in particular) is designed, adding the MonAMI plugin to send it data is very easy. The code is now in CVS, ready for the next release. I've included a few screen shots that show the graph compositor.

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