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

[Danny Milosavljevic]

Hi Ludo,

On Tue, 09 Jan 2018 10:05:34 +0100
address@hidden (Ludovic Courtès) wrote:

> We discussed some time ago the possibility to automatically instantiate
> services.  Now that service types have default value, I think it’s a
> viable approach: if a service is required, and *if* it provides a
> default value, then we can automatically instantiate it.
> 
> So in the example above, you’d just specify ‘rottlog-service-type’ and
> an ‘mcron-service-type’ would be automatically added if it’s not already
> there.

Yes, as long as there's a way for the user to easily see what it instantiated 
(in the running system).

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 ?

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?