Re: gnu-system-demo feedback

[ludo@gnu.org (Ludovic Courtès)]

Walter Franzini <walter.franzini@gmail.com> skribis:

> On Wed, Oct 16 2013, Ludovic Courtès wrote:
>
> [...]
>
>> The files in /etc are symlinks to files under /nix/store, and it’s those
>> files that were removed.  The symlinks were still there, just dangling.
>
> I'm unable to find information about handling of local modification to
> configuration files.

The idea (this is WIP) is to use a purely declarative approach à la
NixOS (see <http://nixos.org/nixos/docs.html>.)

Under this approach, administrators declare all the specifics of the
system-wide configuration: what user accounts are available, what the
default locale is, what file systems are mounted, which services are
started, etc.

The configuration can be “instantiated” and used.  When the admin wants
to change something in the system config, they adjust the declaration
accordingly, instantiate the new configuration, and switch to it.

The obvious advantages of this declarative approach are: control
(there’s a direct mapping from the declaration to its on-disk
instantiation), transactional configuration upgrade, and the ability to
roll back (it’s just a matter of referring to the files that resulted
from the previous instantiation.)

You can look at the (somewhat ugly) ‘system-qemu-image’ procedure in
gnu/system/vm.scm to get an idea of what this looks like here.  It
contains declarations of system services, user accounts, and so on.

HTH,
Ludo’.