Re: "guix pack -f docker" does too much work

[Simon Tournier]

Hi,

On Sat, 01 Jun 2024 at 15:58, Ludovic Courtès <ludo@gnu.org> wrote:

>> I think it would be great if "guix pack -f docker" could avoid building
>> all these identical layers again and again.  Perhaps it would be
>> possible to have a single derivation for each layer?  This way we
>> wouldn't have to recreate the same layer archives every time.
>
> That sounds nice in terms of saving CPU time.  It’s less nice in terms
> of disk usage: a single ‘guix pack -f docker’ run would populate the
> store with roughly twice the size of the closure.
>
> I think each solution (single derivation vs. one derivation per layer)
> makes a different tradeoff.  I don’t have a strong feeling about which
> one is better.

I share Ricardo wish.  From my perspective, I do not care much about
polluting my local Guix store when building Docker images.  Because all
that will be removed at the next GC – once all the work is loaded
elsewhere.

However, it appears frustrating to build again and again complete large
images when the difference is sometimes just a couple of packages.

I would be in favor to share more derivations between images. :-)

Cheers,
simon