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

[ludo@gnu.org (Ludovic Courtès)]

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

> Am 11.11.2017 um 12:31 schrieb Ludovic Courtès:
>> 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.
>
> Not in my case. Plasma heavily relies on plugins and such. I have added
> about 50 package to the system configuration to make Plasma start. Now I
> need [1] to iterately remove (and re-add) packages (not services!) to
> learn what are actual the minimum requirements.
>
> Creating a new VM for each iteration is *much* too time-consuming – no
> matter if using "vm-image" or "vm" –, let alone since this required to
> reboot the machine each time. Even if I would try to write a test-case
> for this [2], each cycle would take too much time.

Well, I’ve always used the above approach to test system services as I
worked on them, and the 10–30 seconds it took for ‘guix system vm’ to
complete as I tweak the service were never that much of a hindrance to
me.

But yeah, I understand you’re using ‘vm-image’, so it’s a different
story since ‘vm-image’ takes ages.

Now, it seems to me that the workflow you describe has become this
complicated just because of the slowness of Plasma in the VM.  To me
that’s something worth investigating.  Granted a VM with a 9p-mounted
store is slower than a bare metal system, but it shouldn’t be this slow.
Something’s wrong.

> On a Fedora-like system I would simply 'rpm -e PACKAGENAME`.
> Unfortunately guix is not able to uninstall a package it does not know
> (see <https://lists.gnu.org/archive/html/guix-devel/2017-11/msg00160.html>).

It cannot uninstall a propagated package, if that’s what you mean.

Ludo’.