Colors of Noise

I recently had the joy to adjust a heating system powered by a Ökofen Pellematic pellet boiler. It turned out that the heating control for that system has a small web interface running on a Linux system that allows one to set the different temperature values.

The different temperature values can be queried easily using python-request and then graphed via a simple munin plugin:

The sources are available here. Several more plugins for the different pumps and switches are already in the works. This needs some more work though to avoid lots of copy and paste.

Sadly enough there's no SSL available in the web interface. I already contacted the vendor about that and about the GPLed parts of their software so there's more to come.

This blog is flattr enabled.

The libvirt munin plugins improved quiet a bit since their initial release:

• I added two more plugins:
  • libvirt-cputime: monitor cpu time used by virtual machines
  • libvirt-mem: monitor the amount of memory used by virtual machines
• these two plugins have adjustable limits for their warning and critical values, see the README for more details
• the plugins now work properly with Xen by special casing Domain-0
• they also ship as a Debian package

Here are two munin plugins that monitor disk and network I/O of virtual machines using libvirt. These are also two simple examples on using the libvirt python bindings. You need python-libvirt and python-libxml2 installed in order to use them. If you don't want to use the default uri, try:

[libvirt-*]
env.uri qemu:///system

Munin-node needs to have read access to libvirt's socket. This is the case in Debian's default installation.