[openstack-dev] [nova] [placement] unresolved topics in resource providers/placement api

Ed Leafe ed at leafe.com
Thu Jul 28 15:52:01 UTC 2016

On Jul 28, 2016, at 9:47 AM, Roman Podoliaka <rpodolyaka at mirantis.com> wrote:

> How about we do a query in two steps:
> 1) take a list of compute nodes (== resource providers) and apply all
> the filters which *can not* (or *are not* at some point) be
> implemented in placement-api
> 2) POST a launch request passing the *pre-filtered* list of resource
> providers.  placement api will pick one of those RP, *claim* its
> resources and return the claim info
> A similar approach could probably be used for assigning weights to RPs
> when we pass the list of RPs to placement api.

That is very similar to the approach I proposed for the live migration API change to accommodate the needs of Watcher: provide a list of potential hosts, and have the scheduler select one from that list. Rather than muck with an existing API, we decided to postpone supporting that until the placement API was available. I think that providing a subset of all resource providers to the placement API to limit the potential results is an important addition, especially with the eventual thought of having this be a generic placement API for all sorts of resources.

-- Ed Leafe

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