From the etherpad [1] (the cross project one):
* This came up with the effort to add a multiattach capability filter, at https://review.openstack.org/#/c/645316/1/nova/compute/api.py@1098 * The problem: we want to be able to request allocation candidates filtered by a trait that exists on the root provider; but * (a) the root provider may provide no resources (eventually - e.g. CPU/mem in NUMA providers, shared disk); and/or * (My brain hurts from the concept for a provider that provides nothing. Perhaps it provides something we aren't remembering to count?) * (b) we are using only numbered groups and would have to guess where to stuff the `required` - again probably based on looking for the VCPU/mem resources, which, as above, may wind up not on the root provider. This, basically, is how/when do we deal with resource providers that have traits but have no classes of inventory of their own (all of it is on their descendants). The "My brain hurts" comment above is mine. The discussion on the review above (good backgrounder for this thread) had little to do with the immediate need of the proposed feature. It was a concern about how things will work in the future. So there are two salient questions (and presumably plenty of other sidebars): * How should it work? * What is the timeline for when it needs to work? [1] https://etherpad.openstack.org/p/ptg-train-xproj-nova-placement -- Chris Dent ٩◔̯◔۶ https://anticdent.org/ freenode: cdent tw: @anticdent