Hi,

> Is there a use-case for certbot without any certificate configurations provided?

I was writing a service that extends certbot if a configuration option
for it is set to #t. To me it seems that it is currently impossible to
view the configuration in the service type definition, so I worked
around it by extending certbot-service-type with an empty list if the
option is set to #f.

> IMO it looks to me that the 'certificates' field shouldn't have a default value
> configured instead?

Wouldn't that mean that users who use certbot only via services that
extend it would have to configure 'certificates' to () manually and have
their nginx configuration crash if they remove the extending services
and forget to remove the certbot service?

- Saku