Re: share guix and its store between distributions

[Daniel Littlewood]

Hi Emmanuel,

Do you expect to share exactly the same packages in Debian vs guix, or
just an overlapping subset?

I assume that if the packages are the same, and they're building the
same versions, then the hash identifying them should be the same, and
guix should refrain from rebuilding the package (and simply set up the
link to the store). If they aren't the same, then you have to make
sure the system A does not clean up any packages used by system B and
not system A. I guess this is why you mention GC roots. My gut feeling
is that that will be a lot more complicated, because you have to trick
guix into getting its garbage collection "wrong".

Perhaps you could keep the two stores separate, but mount them as a
union file system? So system A would mount system B's store into its
own, read-only. System B would be able to build additional packages
not found in A, but could not clean up system A's packages. I don't
know how guix would react to such a permission error. I think it
expects to be the only master of the store.

All the best,
Dan

On Thu, Oct 5, 2023 at 4:04 PM Emmanuel Beffara <manu@beffara.org> wrote:
>
> Hello Guix,
>
> Is there a way to share Guix and its store between several distributions?
>
> My situation is that I have a Guix system installed as my main system, but I
> would like to install another distribution on the same machine (a current
> Debian, specifically) and use Guix as a package manager there, in order to
> benefit from its ability to create reproducible environments.
>
> Of course, it works to have the other distribution completely independent,
> with its own Guix store. The only thing is to handle Grub correctly to give
> access to both distros. But it feels like a significant waste of resources,
> since I will end up having many things in both stores.
>
> Moreover, ideally I would like to share home directories between the two
> distributions, by mounting the same partition as /home, and still be able to
> use `guix home` and `guix shell` in both distributions. By some minimal
> tuning, I can make it so that users have the same UIDs and GIDs in both
> distributions. But I imagine that using Guix in both distributions can become
> problematic if they don't share the store and the state in `/var/guix`, for
> instance if they don't share GC roots.
>
> Is there a proper way to make that work? Or is it a bad idea?
>
> --
> Emmanuel
>