Bug#891836: systemd: systemctl start/stop/restart valid-template at invalid-instance doesn't cause errors

[Michael Biebl]

Am 01.03.2018 um 20:35 schrieb Felipe Sateler:
> On Thu, Mar 1, 2018 at 2:46 PM, Michael Biebl <biebl at debian.org> wrote:
>> Control: tags -1 moreinfo unreproducible
>>
>> Am 01.03.2018 um 16:00 schrieb Martin von Wittich:
>>> Hi Michael,
>>>
>>> On Thu, 1 Mar 2018 15:10:26 +0100 Michael Biebl <biebl at debian.org> wrote:
>>>> I can't reproduce this, neither on v237 nor on v232:
>>>>
>>>> # systemctl stop postgresql at does-not-exist
>>>> Failed to stop postgresql at does-not-exist.service: Unit
>>>> postgresql at does-not-exist.service not loaded.
>>>>
>>>> # systemctl start postgresql at does-not-exist
>>>> Failed to start postgresql at does-not-exist.service: Unit
>>>> postgresql at does-not-exist.service not found.
>>>>
>>>> # systemctl restart postgresql at does-not-exist
>>>> Failed to restart postgresql at does-not-exist.service: Unit
>>>> postgresql at does-not-exist.service not found.
>>>
>>> Do you have a postgresql template installed (should be the case when you
>>> have a postgresql-9.{4,6} (jessie/stretch) server package installed)? If
>>> not, try another template, maybe getty (I hope that's available on every
>>> system, would make reproducing this a lot easier):
>>
>> Hm, right. I completely missed the part about "valid-template", and no,
>> I didn't have postgresql at .service.
>>
>> But I'm not sure if what you are seeing is actually a bug. A templated
>> service does not necessarily need a representation on disk. It is very
>> much possible, that you simply want to pass a command flag to a daemon
>> for example.
>>
>> So systemd will happily start/stop/restart such a noop in your case. The
>> only case where it fails is, on a reload, because there wasn't actually
>> a process running which could be reloaded.
>>
>> Sounds a bit strange but is imho consistent.
>>
> 
> I think the problem is postgres has:
> 
> # -: ignore startup failure (recovery might take arbitrarily long)
> # the actual pg_ctl timeout is configured in pg_ctl.conf
> ExecStart=-/usr/bin/pg_ctlcluster --skip-systemctl-redirect %i start
> 
> If postgres would report the error back to systemd, it would at least
> tell you that.
> 
> getty at .service suffers from the same issue. Other units do not:
> 

You are spot on, Felipe. Afaics, systemd works as designed.
Question is, whether this bug report should be assigned to postgresql to
not use '-'.

CCing Christoph for his input.

Michael
-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?

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