Re: Proposal: auto-instantiate services with a default value

[Ricardo Wurmus <rekado@elephly.net>]

Ludovic Courtès <ludo@gnu.org> writes:

>> Also, that means that the instantiated mcron-service would automatically get a rottlog entry even though the mcron-service-types's default job list is empty, right ?
>
> Correct.
>
>> In that case it would be nice to be able to (optionally) override this mcron-service by a custom mcron-service in /etc/config.scm but retain the modified configuration with the implicit job in it.  Is that possible?
>
> Sure, the current way to do things (which is to explicitly list rottlog
> *and* mcron) would remain valid, and you could pass your own mcron
> config this way.

If a user already had an mcron service with a custom configuration,
it would still be extended as needed by adding the rottlog-service — or
am I mistaken?

I think auto-instantiation is great when it all shows up with “guix
system extension-graph” and users can thus figure out why certain
services were instantiated unexpectedly.

--
Ricardo

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