[systemd-devel] /usr vs /etc for default distro units enablement

[Tom Gundersen]

On Tue, Nov 18, 2014 at 5:11 PM, Michael Biebl <mbiebl at gmail.com> wrote:
> 2014-11-18 14:52 GMT+01:00 Martin Pitt <martin.pitt at ubuntu.com>:
>> Colin Guthrie [2014-11-18 13:01 +0000]:
>>> >  * I suppose even wich such a policy the post-installation script
>>> >    still needs to call some systemd-update-policy-mumble-mumble magic
>>> >    to actually apply the new policy?
>>>
>>> Well, the *.policy files are simply read when calling "systemctl preset"
>>
>> Right. I meant, even with using presets, a newly installed package
>> still needs to call "systemd preset foo.service" for all the units
>> that it ships, so that the /etc symlinks are generated. I. e. we
>> merely replace "enable" (what the current Debian packages do) with
>> "preset" in the postinst.
>>
>> We need to do that as systemd doesn't automagically spot newly
>> installed units (via inotify or what not) and enable them.
>>
>> Or did I misunderstand this?
>>
>>> The idea is that there are very few policy files shipped in a distro
>>
>> Indeed. A generic distro should have exactly one, with "disable *"
>> (Fedora policy) or "enable *" (Debian policy). Anything more special
>> would be customization for specialized images/spins/etc.
>>
>>> >  * With that, how would a package then say that it does *not* want a
>>> >    particular unit to get enabled?
>>>
>>> The idea is that you don't really decide that at a package level, but at
>>> a distro level.
>>
>> We do (and that policy drives the auto-generated postinst), but there
>> are always special cases where a package might want to ship a unit
>> which doesn't get enabled by default. I was wondering how that could
>> be accomodated. So for that, the package itself could ship its own
>> preset file, containing a "disable myself.service"? That would make
>> sense (if I understood it right). Either way, this is certainly the
>> rare exception.
>
> I'm not sure if this preset feature with a single, centrally managed
> and distro-provided file
> is going to work with 1000+ packages shipping sysv init scripts (or in
> the future, systemd .service files).
>
> We really need the flexibility to decide that on a per package basis.


You already have this flexibility right? You can drop in any number of
preset files (even one per package if that makes the most sense).

Cheers,

Tom