[systemd-devel] [RFC] Preset Files

[Ludwig Nussel]

Lennart Poettering wrote:
> <snip>
> disable avahi-daemon.service
> enable cups.service
> disable *
> </snip>

I suppose evaluation stops as soon as an entry matches. So as Distro
we could have e.g 99-default "disable *" as default policy.

> - The RPM post macro would always call "systemctl preset" for the units
>   passed, and never anything else.

What happens if the preset lists the service as enabled but the admin
has disabled it manually? Will a package or distro upgrade re-enable
the service? I suppose systemd needs to store somehere whether a
preset was already applied for each service.

> - The reason why we'd implement "enable-by-default" instead of
>   "disable-by-default" if no preset file is around is simply the idea
>   that having to install stuff that is not needed is already a failure
>   in itself, and ideally people who want to disable a service would just
>   "rpm -e" it.

That's not quite the case, think of e.g. openssh where you may want
the client but not the server¹ or mysqld which is used by kde per
user or avahi where you may want avahi-daemon but not avahi-dnsconfd
:-) However, that ok as long as we can put a "disable *" by default
somewhere.

> Anyway, this of course requires some buy-in from the distributions, so
> I'd like to ask the distro maintainers for comments on this. Do you
> think this would be useful to you? Any other suggestions, ideas?

Good idea in general. Checking simple files instead of trying to
make sense of shell code in %post also makes life easier for rpmlint.

cu
Ludwig

[1] back in the days when we nearly got lynched for disabling sshd
by default we explicitly decided not to split the package in client
and server.

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