Bug#898388: systemd-sysv: shutdown command always fails

[Meeuwissen Olaf]

Hi,

Michael Biebl writes:

> Am 11.05.2018 um 08:10 schrieb Meeuwissen Olaf:
>> Hi,
>>
>> Thanks for the quick follow-up.
>>
>> Michael Biebl writes:
>>
>>> Control: tags -1 + moreinfo
>>>
>>>> I have set up unattended-upgrades to reboot my machine at 04:00 when
>>>> necessary.  Internally, unattended-upgrades runs
>>>>
>>>>   /sbin/shutdown -r 04:00
>>>>
>>>> trying to achieve this.  This fails as evidenced by these (dated) log
>>>> messages
>>>>
>>>>   Apr 25 06:55:18 easy apt.systemd.daily[38369]: Found /var/run/reboot-required, rebooting
>>>>   Apr 25 06:55:18 easy apt.systemd.daily[38369]: Failed to connect to bus: No such file or directory
>>>
>>> What's the output of
>>> systemctl status dbus.socket dbus.service systemd-logind.service
>>
>>   $ sudo systemctl status dbus.socket dbus.service systemd-logind.service
>>   Unit dbus.socket could not be found.
>>   Unit dbus.service could not be found.
>>   * systemd-logind.service - Login Service
>>      Loaded: loaded (/lib/systemd/system/systemd-logind.service; static; vendor preset: enabled)
>>      Active: inactive (dead)
>>   Condition: start condition failed at Fri 2018-05-11 04:00:25 JST; 10h ago
>>              `- ConditionPathExists=/lib/systemd/system/dbus.service was not met
>>        Docs: man:systemd-logind.service(8)
>>              man:logind.conf(5)
>>              http://www.freedesktop.org/wiki/Software/systemd/logind
>>              http://www.freedesktop.org/wiki/Software/systemd/multiseat
>>
>> Yes, I don't have dbus installed.  Nothing I have installed has a
>> dependency on it that is Depends: or more important.  I don't install
>> Recommends: and actively remove them unless other installed packages
>> declare a (Pre-)Depends:
>>
>> Based on my understanding of the relevant section[1] in the Debian
>> Policy, I would argue that systemd-sysv needs a Depends: dbus.
>>
>>  [1]: https://www.debian.org/doc/debian-policy/#binary-dependencies-depends-recommends-suggests-enhances-pre-depends
>>
>> The Recommends: that systemd declares looks fine as I have not observed
>> any other breakage.
>>
>> FTR, after I install dbus, I get
>>
>>   $ sudo shutdown -r 04:00
>>   Shutdown scheduled for Sat 2018-05-12 04:00:00 JST, use 'shutdown -c' to cancel.
>>
>
> Scheduled shutdowns require systemd-logind, which in turn requires
> dbus.

In my initial bug report I included

  root at debian:~$ shutdown -r 04:00
  Failed to connect to bus: No such file or directory
  root at debian:~$ shutdown -r
  Failed to connect to bus: No such file or directory
  root at debian:~$ shutdown
  Failed to connect to bus: No such file or directory

What is scheduled about the last two commands?  The implicit "now"?

The reboot command, also provided by systemd-sysv, works *without* dbus
installed.  So do the halt and poweroff commands.

The only thing login related I could find in the shutdown manual page is
the creating of a /run/nologin file in case a timespec is given.

> The basic functionality of systemd does not strictly require dbus
> though. This pretty much fits the bill for recommends and we want to
> allow (at least for the time being), to not have dbus installed, even if
> this means, that certain functionality in systemd is then not available.
> This is a choice the admin has to make.

And I agreed that the Recommends: dbus for systemd is fine.  I said that
I thought that systemd-sysv needs a Depends: because the absence of dbus
breaks the shutdown command *completely*.

# OK, so invoking it with the --help option works.  Great!

I would think completely breaking the shutdown command meets

  The Depends field should be used if the depended-on package is
  required for the depending package to provide a significant amount of
  functionality.

unless you want to argue that shutdown is not a significant amount of
functionality provided by systemd-sysv.

Seeing that systemd does not depend on systemd-sysv, adding the dbus
dependency to systemd-sysv will not introduce a dbus dependency for
systemd itself.

> If you choose to not install dbus, then you can't use logind (and as
> such scheduled shutdowns).
>
> So everything is behaving as expected.

Definitely not from my POV.  I'm off now installing dbus myself because
systemd-sysv didn't think it important enough to do that for me :-(

Hope this helps,
--
Olaf Meeuwissen, LPIC-2       FLOSS Engineer -- EPSON AVASYS CORPORATION
       Free Software Foundation Associate Member since 2004-01-27
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