[Pkg-systemd-maintainers] [Pkg-utopia-maintainers] Bug#734460: Bug#734460: network-manager: Issues related to systemd when upgrading from << 0.9.8.8-2

[Michael Biebl]

Am 12.01.2014 13:11, schrieb Laurent Bigonville:
> Le Sun, 12 Jan 2014 02:18:32 +0100,
> Michael Biebl <biebl at debian.org> a écrit :
> 
>> Am 07.01.2014 13:12, schrieb Laurent Bigonville:
>>> Package: network-manager
>>> Version: 0.9.8.8-2
>>> Severity: serious
>>>
>>> Hi,
>>>
>>> I'm opening this bug so this is not getting lost.
>>>
>>> When upgrading from the previous versions the following events might
>>> occurs when the user is running systemd:
>>>
>>> 1) The package was not enabling the systemd unit in the previous
>>> versions.
>>> 2) NM was then started using the LSB script called network-manager.
>>> This means that the cgroup was called network-manager.service.
>>> 3) During the upgrade the systemd unit is properly enabled and the
>>> LSB script is masked by a symlink, this means that at some point
>>> during the upgrade, the canonical name changes from
>>> network-manager.service to NetworkManager.service
>>> 4) At the end of the upgrade, systemd looks for a
>>> NetworkManager.service cgroups which is not existing and then
>>> concludes that the service is not running at all.
>>> 5) Systemd tries to start the service, NM complains that there is an
>>> other instance of itself running => boom
>>>
>>> To fix this, I would propose to stop NM in the preinst script if we
>>> are upgrading from the previous versions and that the user is
>>> running systemd.
>>
>> Why preinst and not postinst (before the #DEBHELPER# stanza, i.e.
>> before the service is enabled)?
>> Stopping the service in preinst creates unnecessary downtime which
>> could be fatal if NM is in charge of the network connection and you
>> do a remote upgrade.
>> I don't see a downside moving the network-manager stop to postinst, do
>> you? Just in case I'm missing something
> 
> Well, in the postinst the symlink that mask the LSB will already be
> present on disk. That means that the canonical name of the service has
> already changed. A daemon-reload is actually needed for systemd to
> notice this change, but nothing guarantee that no other packages would
> do it for us between the moment the files are unpacked and the moment
> our postinst script is called.

Ah, k. I missed the part about the symlink/alias now being shipped
directly in the package and it no longer being created via
[Install]
Alias=network-manager.service


> That's why I thought that stopping the service in the preinst was the
> safer choice.

This somehow smells like the same bug as [1] or at least related, i.e.
systemd getting confused when we mess around with the symlinks.	
(In case of rsyslog we basically go the other direction: the symlinks
are no longer shipped in the package but created on install time via
dh-systemd)
I wonder if there is a way to address this directly in systemd.

Michael

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=724796
-- 
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