Re: how to create and test a new service definition

[ng0]

On Sun, 14 May 2017, Catonano wrote:

> 2017-05-13 22:06 GMT+02:00 Ludovic Courtès <address@hidden>:
>
> > Vincent Legoll <address@hidden> skribis:
> >
> > > > The best way to test your code is to write an ‘operating-system’
> > > > declaration that uses the new service and to instantiate it in a VM with
> > > > ‘guix system vm’.
> > >
> > > Should that be working properly (out-of-the-box) when you're already in
> > > a qemu VM (recursive virtualization) ?
> > >
> > > I ask because I'm getting:
> > >
> > > [...]
> > > ERROR: qemu failed "qemu-system-x86_64"
> >
> > What were the lines above this one?  This tool tries to use KVM if it
> > seems available.  Maybe in your case it “seems” to be available (as in
> > /dev/kvm exists) but is actually unusable?
> >
> > > > Once you’ve done that, you can also write an automated test for the new
> > > > service; see <https://gnu.org/s/guix/news/guixsd-system-tests.html>.
> > >
> > > I'm far from there, I have a *really* hard time getting back to guixsd.
> > For
> > > instance it took me very long time to find back the GUIX_PACKAGE_PATH
> > > env var. This looks under-documented, or I don't understand how one is to
> > > work on custom or new packages, etc...
> >
> > ‘GUIX_PACKAGE_PATH’ is documented at
> > <https://www.gnu.org/software/guix/manual/html_node/Package-
> > Modules.html#index-GUIX_005fPACKAGE_005fPATH>.
> >
> > The workflow for defining packages is described at
> > <https://www.gnu.org/software/guix/manual/html_node/Defining-Packages.html
> > > ,
> > and that for contributing them is at
> > <https://www.gnu.org/software/guix/manual/html_node/
> > Submitting-Patches.html>.
> >
> > There’s probably room for improvement though.  What changes/additions
> > would you suggest?
>
> Let me chime in here: I'd suggest to state the workflow or defining
> services, as the one or deining packages is stated
>
> But I'm not thinking about how to define and use The scheme structures. The
> examples are enough for that.
>
> I'm thinking about things like how to deal with qemu, if you want to test
> your services in a vm
>
> Is there any other way to get your feet wet with services ?
>
> George suggested me the trick to link a checked out master branch to
> .local/guix/profile (or maybe it's the other way around: it's liinking
> .local/guix/profile to a checked out master branch)
>
> Is anyone using this to work on services ? How, exactly ?
>
> Thanks

My current way of testing services is usually on bare-metal.
I had bad experiences with one network based service (gnunet)
and it being terrible to debug, so I took the QEMU out of there.
I test things this way which will not break my current generation 
like darkhttpd or the gopherd I submitted as a question.
Other, potential boot breaking, stuff I test on other systems.

This is also because I never really figured out the best way
to run network based services in qemu in Guix. I have no issues
with qemu, but on Guix many months back it behaved unlike the
qemu I knew from Gentoo.

There is lots of room for services in the documentation.
There should be a "contributing services" section in chapter 8,
currently I learn this the way I learned to do packages, by
repetition and failure until I see how to debug stuff.. which is already 
helping since I am starting to see patterns for debugging with darkhttpd 
(it helped that it simply worked and then randomly broke in further 
attempts).