[systemd-devel] Special targets - should they Want or be WantedBy?

[Andrey Borzenkov]

On Thu, Mar 17, 2011 at 1:59 PM, Mike Kazantsev <mk.fraggod at gmail.com> wrote:
> On Thu, 17 Mar 2011 12:41:34 +0300
> Andrey Borzenkov <arvidjaar at mail.ru> wrote:
>
>> On Thu, Mar 17, 2011 at 11:06 AM, Mike Kazantsev <mk.fraggod at gmail.com> wrote:
>> > On Thu, 17 Mar 2011 01:04:35 +0100
>> > Lennart Poettering <lennart at poettering.net> wrote:
>> >> If DefaultDependencies= is "yes" (which it is by default) for target
>> >> units then they'll automatically gain an After= for all untis they have
>> >> Wants= or Requires= on.
>>
>> > Can this behavior be relied upon or this might change in future
>> > releases?
>> >
>> > It's just that this magic bit makes After= line in lots of units I've
>> > seen (and wrote) redundant, so can it be dropped and skipped in any
>> > new units or it's better to be explicit in this case?
>> >
>>
>> Do you have that many target units?
>
> Ah, I missed the "target units" part, but even then
> "Requires=network.target + After=network.target" is a common
> enough pattern for services that need network to be up at startup and
> After= line is present in each one of them:
>

Dependencies are added to target for units that it pulls. Not other way round.

>  /lib/systemd/system/noip.service:Requires=network.target
>  /lib/systemd/system/dnscache.service:Requires=network.target
>  /lib/systemd/system/tinydns.service:Requires=network.target
>  /lib/systemd/system/remote-fs.target:Requires=network.target
>  /lib/systemd/system/ziproxy.service:Requires=network.target
>  /lib/systemd/system/ejabberd.service:Requires=network.target
>  /lib/systemd/system/dhcpd.service:Requires=network.target

I tentatively think that these should be either After or Requisite. Do
you really want to start network every time one of those services gets
started (assuming there were reasons to have network stopped at this
moment)?