gnu-system-demo feedback

gnu-system-demo feedback

[Walter Franzini]

Hi,

being curious about guix I've tried to use the gnu-system-demo image and
I've found some difficulties:

1. how to shutdown the system?
2. guix pull fails - already reported by someone else
3. running guix gc as root empties /etc (broken symlinks)
4. running guix gc as guest (!) empties /etc (broken symlinks)
5. df fails with the following message
   df: cannot read table of mounted file systems.  No such file or directory

I'm missing something?
Can someone point me to relevant information?

thank you
-- 
walter franzini

gnu-system-demo feedback

[Walter Franzini]

[message resent, my apologies if someone receive it twice]

Hi,

being curious about guix I've tried to use the gnu-system-demo image and
I've found some difficulties:

1. how to shutdown the system?
2. guix pull fails - already reported by someone else
3. running guix gc as root empties /etc (broken symlinks)
4. running guix gc as guest (!) empties /etc (broken symlinks)
5. df fails with the following message
   df: cannot read table of mounted file systems.  No such file or directory

I'm missing something?
Can someone point me to relevant information?

thank you
-- 
walter franzini

Re: gnu-system-demo feedback

[Ludovic Courtès]

Hi, Walter,

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

> being curious about guix I've tried to use the gnu-system-demo image and
> I've found some difficulties:
>
> 1. how to shutdown the system?

Why would one do such a thing?  ;-)

There’s currently no ‘shutdown’ command, because dmd (the init system)
doesn’t have one yet.  Its support for run levels is preliminary.
Adding good support for that is the next thing to do.  See
<http://www.gnu.org/software/dmd/manual/dmd.html#Runlevel-evolution> for
more info.

> 2. guix pull fails - already reported by someone else

Yes, that’s now fixed, but the version in the image is broken.

> 3. running guix gc as root empties /etc (broken symlinks)
> 4. running guix gc as guest (!) empties /etc (broken symlinks)

A bug: I forgot to register them as GC roots (see gnu/system/vm.scm.)

> 5. df fails with the following message
>    df: cannot read table of mounted file systems.  No such file or directory

I believe that’s because /etc/mtab is missing.

> I'm missing something?
> Can someone point me to relevant information?

I don’t think you’re missing anything, except that this was preliminary
work.  All this clearly needs to be ironed out, and that will be part of
the focus for the next releases.

The areas where help is appreciated are the system-wide configuration
instantiation tools (the gnu/system/*.scm modules), and dmd
(http://www.gnu.org/software/dmd/).  dmd is quite small, which makes it
easy to get started with it, I think.

Thanks for your feedback,
Ludo’.

Re: gnu-system-demo feedback

[Walter Franzini]

On Mon, Oct 14 2013, Ludovic Courtès wrote:

[...]

>> 3. running guix gc as root empties /etc (broken symlinks)
>> 4. running guix gc as guest (!) empties /etc (broken symlinks)
>
> A bug: I forgot to register them as GC roots (see gnu/system/vm.scm.)

Ok for the bug about GC roots, but I expected a 'guest' not to be able
to alter the system state (/etc).

ciao
-- 
walter franzini

Re: gnu-system-demo feedback

[Ludovic Courtès]

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

> On Mon, Oct 14 2013, Ludovic Courtès wrote:
>
> [...]
>
>>> 3. running guix gc as root empties /etc (broken symlinks)
>>> 4. running guix gc as guest (!) empties /etc (broken symlinks)
>>
>> A bug: I forgot to register them as GC roots (see gnu/system/vm.scm.)
>
> Ok for the bug about GC roots, but I expected a 'guest' not to be able
> to alter the system state (/etc).

Unprivileged users can access the store via the daemon.  Notably, they
can run the GC.

The GC only ever deletes files that are no longer referenced.  These
/etc files were clearly still referenced, but the GC just didn’t know
about it.

Ludo’.

Re: gnu-system-demo feedback

[Ludovic Courtès]

ludo@gnu.org (Ludovic Courtès) skribis:

> Walter Franzini <walter.franzini@gmail.com> skribis:
>
>> On Mon, Oct 14 2013, Ludovic Courtès wrote:
>>
>> [...]
>>
>>>> 3. running guix gc as root empties /etc (broken symlinks)
>>>> 4. running guix gc as guest (!) empties /etc (broken symlinks)
>>>
>>> A bug: I forgot to register them as GC roots (see gnu/system/vm.scm.)
>>
>> Ok for the bug about GC roots, but I expected a 'guest' not to be able
>> to alter the system state (/etc).
>
> Unprivileged users can access the store via the daemon.  Notably, they
> can run the GC.
>
> The GC only ever deletes files that are no longer referenced.  These
> /etc files were clearly still referenced, but the GC just didn’t know
> about it.

I probably wasn’t clear.  The GC only takes care of files under
/nix/store, and it cannot remove anything outside of that directory.

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.

Ludo’.

Re: gnu-system-demo feedback

[Walter Franzini]

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.

thanks for your eplanations.
-- 
walter franzini

Re: gnu-system-demo feedback

[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’.