OK, I found it in build-aux/hydra/demo-os.scm


On Fri, Apr 18, 2014 at 1:30 PM, Elric Erkose <elric.erkose@gmail.com>wrote:

> I wanted to play with guix, in particular whole "System Configurartion".
> The example in the documentation does not work for me. Would someone
> provide a link to the configuration used to build gnu-system-demo-0.6.qcow2
>
> Thanks
>