Thursday 1 October 2020

Re: systemd PathExists triggers

Conditions* are unaffected at all, and are unrelated to the issue at
hand whatsoever.

On Thu, 1 Oct 2020 at 08:33, Christian Ehrhardt
<christian.ehrhardt@canonical.com> wrote:
>
> On Wed, Sep 30, 2020 at 7:43 PM Brian Murray <brian@ubuntu.com> wrote:
> >
> > Recently there was a systemd change regarding PathExists for
> > systemd.path units that made systemd behave the way it was documented to
> > work. The effect being that if the PathExists or PathExistsGlob
> > condition is met the service is continually started which may not be the
> > behavior some packages expect as it didn't used to work that way.
> >
> > As an example apport's autoreport service uses PathExistsGlob to check
> > for a .crash file and then calls whoopsie-upload-all which used to run
> > once when the .crash file appeared. As of Groovy whoopsie-upload-all was
> > called continuously thereby causing systemd to use 100% of your CPU[1].
> >
> > While this is resolved for apport's case, the Foundation's team thought
> > it was worth mentioning as other package's services may also be
> > impacted.
>
> Thanks Brian for your warning!
> I see in your list some .path files e.g. the aforementioned
> apport-autoreport.path
> that I understand if using a PathExist* will have changed. Of those the list [2]
> contains 9 to look at.
>
> I beg your pardon, but the list is vast due to including any
> "Type=oneshot" as well.
> And from the summary you gave I don't see why those are included as well.
> Looking at the first in the list that probably everyone has installed I see:
> a)
> /lib/systemd/system/alsa-restore.service there are no associated .path
> files, only
> ConditionPathExists in the unit itself - are those also affected?
> b)
> Looking slightly further /lib/systemd/system/apt-daily.service even
> has no associated
> .path nor any *Exist* statement.
>
> My question would now be - are those files of type (a) or (b) all also
> affected in
> some way or is the "critical list" actually much shorter? I was wondering if you
> could help to clarify before everyone that feels responsible for a package with
> a file in that list is diving into and re-understanding the case.
>
> Thanks in advance,
> Christian
>
> > An archive search[2] (thanks Seth!) was done of services which are
> > Type=oneshot or utilize a PathExists or PathExistsGlob. Briefly scanning
> > the list the following packages should probably be looked at:
> >
> > mandos-client
> > ostree
> > python-diskimage-builder
> > ubuntu-report
> >
> > [1] http://launchpad.net/bugs/1891657
> > [2] https://paste.ubuntu.com/p/k5Gj7rQ9FX/
> >
> > Cheers,
> > --
> > Brian Murray
> >
> > --
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> > ubuntu-devel@lists.ubuntu.com
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>
>
>
> --
> Christian Ehrhardt
> Staff Engineer, Ubuntu Server
> Canonical Ltd
>
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--
Regards,

Dimitri.

--
Regards,

Dimitri.

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