[Pkg-systemd-maintainers] Meta dependencies in unit files?

[Michael Biebl]

Am 21.08.2013 21:13, schrieb Michael Stapelberg:
> Hi Moritz,
> 
> Sorry for the late reply.
> 
> Moritz Muehlenhoff <jmm at inutil.org> writes:
>> I've been studying some unit files and I stumbled upon Fedora's service file
>> for clamav-milter: 
>> http://pkgs.fedoraproject.org/cgit/clamav.git/tree/clamav-milter.systemd
>>
>> I contains the following snipped in the [Unit] section:
>>
>> | Before = sendmail.service
>> | Before = postfix.service
>>
>> Is there the equivalent of Debian's "Provides: mail-transport-agent"
> I think currently there isn’t. Maybe this can be solved by having a
> mail-transport-agent.target, but I don’t claim that I understand targets
> and all their implications well enough yet to tell for sure :). Maybe
> you can experiment a bit and let us know your findings?
> 

There was a mail-transport-agent target for this very purpose in older
systemd releases. It got removed in v198:


        * This release drops support for a few legacy or
          distribution-specific LSB facility names when parsing init
          scripts: $x-display-manager, $mail-transfer-agent,
          $mail-transport-agent, $mail-transfer-agent, $smtp,
          $null. Also, the mail-transfer-agent.target unit backing
          this has been removed. Distributions which want to retain
          compatibility with this should carry the burden for
          supporting this themselves and patch support for these back
          in, if they really need to. Also, the facilities $syslog and
          $local_fs are now ignored, since systemd does not support
          early-boot LSB init scripts anymore, and these facilities
          are implied anyway for normal services. syslog.target has
          also been removed.

That said, we'd also need to add support to parse insserv.conf(.d) files
for this to work fully [1] or tell affected packages to add Provides:
$mail-transfer-agent to their LSB header.
Afaik, insserv doesn't handle this properly though.

That ensures, that starting e.g. postfix.service will activate
mail-(transfer|transport)-agent.target

I'm no longer sure, if we should actually go that route of parsing
insserv.conf(.d) from with systemd core. We might be able to get away
with a generator.

Michael

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=690892
-- 
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universe are pointed away from Earth?

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