Re: Divvying up service definitions

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hi Bruno,

Bruno Victal <mirai@makinata.eu> writes:

> Hi,
>
> As the gnu/services and gnu/home/services grow, I think we should
> consider divvying the services into stand-alone modules or
> subdirectories.
>
> Consider the ⌜dovecot-service-type⌝ in gnu/services/mail.scm: as of
> commit 'd22d2a05c389207f8cdcf824be7738b1499a987c' this service
> definition is nearly 1600 lines long, with the remainder of the file
> comprising of four other services with rudimentary support.
>
> It becomes troublesome working with such amalgamations as it makes it
> hard to keep track of the used modules and bindings, especially when
> define-configuration is used since the serializing procedures might be
> used by various service definitions. Further complicating things is
> 'define-maybe', whose use monopolizes the predicate and serializers for
> a particular service definition.
>
> Now, I'm not saying that we should go and split everything into its own
> module, I'm saying that we should be allowed to split some of them if
> convenient (all subjective but I believe we can see that working with a
> monolithic file in the kilolines where the interactions aren't obvious
> is not fun, and that's without bringing in the hygienic issues
> surrounding define-configuration and define-maybe).
>
> Some considerations (using dovecot-service-type as an example):
> * Splitting this as gnu/services/mail/dovecot.scm.
>   We preserve the logical grouping of the services (with the addition
>   that, for extremely comprehensive definitions, these can be neatly
>   organized into subdirectories. (same structure seen with gnu/*.scm)
>   A drawback is that 'use-service-modules' might not work with this
>   although I wonder whether 'use-service-modules' & co. provide any
>   value if we are already doing '(use-modules (gnu) …)' to begin with.
>   They look redundant IMO.
>
> * Splitting this as gnu/services/dovecot.scm.
>   We keep it compatible with 'use-service-modules' at the cost of having
>   a multitude of files under gnu/services, without any logical grouping
>   (messy).

That's a great initiative!  I agree that multiple 'define-configuration'
services per file can be a bit messy, having to use prefixes everywhere,
making the definitions more verbose.

I don't have a strong preference of the caterogization of services, but
would perhaps prefer the first one (gnu/services/mail/dovecot.scm),
which could then make it easy to offer some interface as
gnu/services/mail.scm that'd re-export all that is needed (would that
work, or reintroduce the same top-level clashes?).

-- 
Thanks,
Maxim