Re: Best-practice to "develop" a system-config / service?

[ludo@gnu.org (Ludovic Courtès)]

Hi Hartmut,

Hartmut Goebel <h.goebel@crazy-compilers.com> skribis:

> I made KDE Plasma start up in a VM by adding tons of packages to the
> system declaration (to be on the save side). Now for finishing and
> providing a nice service declaration I need to strip this list of
> packages down to the bare minimum.
>
> Since a vm (sharing the host store) is unacceptable sloooooow,

Could you be more specific?  I understand from Chris Baines’ measurement
some time ago that it’s definitely slower than a bare-metal system, but
I don’t find it “unacceptably slow” when it comes to testing stuff like
this (it’s definitely faster than building a standalone image with ‘guix
system vm-image’ anyway!).

> I've build a vm-image using my development environment
> ("./pre-inst-env guix system vm-image …"). Now within the VM-image
> there is a different version of guix installed than the in-development
> one I used for building the VM. Of course the former one does not know
> any of the packages I've just added. So I can't not just run "guix
> system reconfigure …".
>
> After some luckless tries I assume the easiest solution would be to get
> my in-development version of guix into the VM. How to achieve this?

You probably don’t want to do that.

I think all you want, to test your KDE service, is to:

  1. Write an OS config that uses the service.

  2. Run “./pre-inst-env guix system vm that-config.scm”, run the VM,
     and check if it works.

That’s really all it takes to develop and test a system service.

You seemed to be willing to start a GuixSD VM that does *not* use the
service you want to test, and then to reconfigure that VM from the
inside so that it would run your service.  That’s super tedious, as you
wrote, and it’s strictly equivalent to the steps above anyway.

HTH!

Ludo’.