[openstack-dev] [nova][placement] scheduling with custom resouce classes

Balazs Gibizer balazs.gibizer at ericsson.com
Mon Jul 17 15:31:22 UTC 2017

On Thu, Jul 13, 2017 at 11:37 AM, Chris Dent <cdent+os at anticdent.org> 
> On Thu, 13 Jul 2017, Balazs Gibizer wrote:
>> /placement/allocation_candidates?resources=CUSTOM_MAGIC%3A512%2CMEMORY_MB%3A64%2CVCPU%3A1" 
>> but placement returns an empty response. Then nova scheduler falls 
>> back to legacy behavior [4] and places the instance without 
>> considering the custom resource request.
> As far as I can tell at least one missing piece of the puzzle here
> is that your MAGIC provider does not have the
> 'MISC_SHARES_VIA_AGGREGATE' trait. It's not enough for the compute
> and MAGIC to be in the same aggregate, the MAGIC needs to announce
> that its inventory is for sharing. The comments here have a bit more
> on that:
> https://github.com/openstack/nova/blob/master/nova/objects/resource_provider.py#L663-L678

Thanks a lot for the detailed answer. Yes, this was the missing piece. 
However I had to add that trait both the the MAGIC provider and to my 
compute provider to make it work. Is it intentional that the compute 
also has to have that trait?

I updated my script with the trait. [3]

> It's quite likely this is not well documented yet as this style of
> declaring that something is shared was a later development. The
> initial code that added the support for GET /resource_providers
> was around, it was later reused for GET /allocation_candidates:
>     https://review.openstack.org/#/c/460798/

What would be a good place to document this? I think I can help with 
enhancing the documentation from this perspective.

Thanks again.

> --
> Chris Dent                  ┬──┬◡ノ(° -°ノ)       
> https://anticdent.org/
> freenode: cdent                                         tw: @anticdent

[3] http://paste.openstack.org/show/615629/

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