[openstack-dev] [nova] Is this a correct use of scheduler hints and nova-scheduler

Sylvain Bauza sbauza at redhat.com
Wed Dec 7 08:38:38 UTC 2016

Le 07/12/2016 04:21, Zhenyu Zheng a écrit :
> Hi all,
> I want to ask a question about using scheduler-hints, could we add
> custom scheduler keys to work with our custom filters? Is it designed to
> allow vendors add own custom filters and keys?

I tend to disagree with that approach from an interoperability
perspective as two clouds could behave very differently.

That said, there is a long-standing problem about scheduler hints being
extensible with regards to our API input validation [1] and we basically
agreed on allowing to relax the constraints [2].

Long story short, you *can* technically do that for a custom filter but
please take care of the communication you make around that new hint to
your customers and make it clear that this hint is not interoperable.

Also, I beg you to make sure that the hint name is self-explanatory and
enough distinct from the other hints we already have so that a confusion
could be minimal.

> Another question is, as we have now persistent scheduler-hints in
> request spec, is it possible to show the scheduler-hints either in
> server-show or a new API? Because vendors may be interested to have an
> idea on how this instance was built in the first place.

Well, I'd say it would be an admin or owner information, but yeah that
could be worth to be exposed.
AFAIK, there is no current way to get that so a blueprint with a spec
describing the problem and the proposal (including an API microversion)
could be interesting to review.


[1] http://lists.openstack.org/pipermail/openstack-dev/2015-June/067996.html


> Thanks.
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