[ClusterLabs] 99-VirtualDomain-libvirt.conf under control - ?

[Andrei Borzenkov]

On Fri, May 5, 2023 at 12:10 PM lejeczek via Users
<users at clusterlabs.org> wrote:
>
>
>
> On 05/05/2023 10:08, Andrei Borzenkov wrote:
> > On Fri, May 5, 2023 at 11:03 AM lejeczek via Users
> > <users at clusterlabs.org> wrote:
> >>
> >>
> >> On 29/04/2023 21:02, Reid Wahl wrote:
> >>> On Sat, Apr 29, 2023 at 3:34 AM lejeczek via Users
> >>> <users at clusterlabs.org> wrote:
> >>>> Hi guys.
> >>>>
> >>>> I presume these are a consequence of having resource of VirtuaDomain type set up(& enabled) - but where, how cab users control presence & content of those?
> >>> Yep: https://github.com/ClusterLabs/resource-agents/blob/v4.12.0/heartbeat/VirtualDomain#L674-L680
> >>>
> >>> You can't really control the content, since it's set by the resource
> >>> agent. (You could change it after creation but that defeats the
> >>> purpose.) However, you can view it at
> >>> /run/systemd/system/resource-agents-deps.target.d/libvirt.conf.
> >>>
> >>> You can see the systemd_drop_in definition here:
> >>> https://github.com/ClusterLabs/resource-agents/blob/v4.12.0/heartbeat/ocf-shellfuncs.in#L654-L673
> >>>
> >> I wonder how much of an impact those bits have on the
> >> cluster(&more?)
> >> Take '99-VirtualDomain-libvirt.conf' - that one poses
> >> questions, with c9s 'libvirtd.service' is not really used or
> >> should not be, new modular approach is devised there.
> >> So, with 'resources-agents' having:
> >> After=libvirtd.service
> >> and users not being able to manage those bit - is that not
> >> asking for trouble?
> >>
> > it does no harm (missing units are simply ignored) but it certainly
> > does not do anything useful either. OTOH modular approach is also
> > optional, so you could still use monolithic libvirtd on cluster nodes.
> > So it is more a documentation issue.
> Not sure what you mean by 'missing unit' - unit is there
> only is not used, is disabled. What does
> 'resource-agents-deps' do with that?

systemd ordering dependencies are only relevant if two units are
started/stopped at the same time. Otherwise it does nothing. You can
compare it with the optional kind of ordering constraint in pacemaker.

> I don't suppose upstream, redhat & others made that effort,
> those changes with the suggestions to us consumers - do go
> back to "old" stuff.

Just because you can do something does not mean you must do it. If the
solution to this issue is to use libvirtd, you need very good
arguments why using libvirtd is not possible.

> I'd suggest, if devel/contributors read here - and I'd
> imagine other users would reckon as well - to enhance RAs,
> certainly VirtualDomain, with a parameter/attribute with
> which users could, at least to certain extent, control those
> "outside" of cluster, dependencies.
>

Manual parameter certainly sounds wrong here. Sort of auto-detection
whether a modular or monolithic installation is active may be useful -
*if* you cannot use libvirtd.