Stephen Gran <stephen.g...@theguardian.com> wrote on 09/27/2013 04:26:37
AM:
> Maybe I'm missing something obvious, but I'm not convinced all that
> logic belongs in Heat. I would expect nova and related components to
> expose grouping information (availability zones in nova, networks in
> quantum, etc) and for end users to supply the "group by" information.
Yes, this additional policy information is not intended to inform
infrastructure orchestration. It is intended to inform something that I
have been calling holistic infrastructure scheduling and others have
called things like unified resource placement and smart resource
placement. I frame it as an extension to Heat templates because this
policy information needs to be added to a statement about a whole
pattern/template/topology and Heat templates are the language we have for
such things. The idea is that holistic infrastructure scheduling comes
before infrastructure orchestration; by the time infrastructure
orchestration happens, the policy information has been handled and removed
(or, possibly, encapsulated in some way for downstream processing --- but
that's another story I am not trying to broach yet).
I have been discussing this outline here under the subject "Bringing
things together for Icehouse" (
http://lists.openstack.org/pipermail/openstack-dev/2013-September/015118.html
), in the scheduler subgroup and heat weekly IRC meetings, and have a
design summit proposal (http://summit.openstack.org/cfp/details/113).
> I think that your use case for anti-collocation (which is a very good
> and important use case, don't get me wrong) is covered by using
> availability zones/cells/regions and so on as they are, and doesn't
> require much logic internal to Heat beyond obeying the constraint
> specified by a user.
If there are five racks in the system and I want to say that two VMs
should be placed on different racks, how do I say that with AZs without
being overly specific?
Thanks,
Mike
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