[openstack-dev] [nova] placement/resource providers update 28

Chris Dent cdent+os at anticdent.org
Fri Jul 14 16:50:06 UTC 2017

Placement update 28.

# What Matters Most

Still claims in the scheduler. It's getting closer, the current
hiccup is dealing with things like a resize on the same host. Diligent
work and discussion in progress. The related changes are in the stack


# What's Changed

Lots of refactoring in the scheduler related unit tests.

# Help Wanted

Areas where volunteers are needed.

* General attention to bugs tagged placement:

# Main Themes

## Claims in the Scheduler

As linked above, the claims in the scheduler work is in this stack:


## Custom Resource Classes for Ironic

A spec for custom resource classes is being updated to reflect the
need to update the flavor and allocations of a previously allocated
ironic node that how has a custom resource class (such as


Work has started on the implementation of that, today, but as far as I
can see nothing is up for review yet, will be soon. This functionality
needs to be in place or we will be continuing to manage ironic
inventory poorly, for another entire cycle.

## Traits

The concept of traits now exists in the placement service, but
filtering resource providers on traits is in flux. With the advent
of /allocation_candidates as the primary scheduling interface, that
needs to support traits. Work for that is in a stack starting at


It's not yet clear if we'll want to support traits at both
/allocation_candidates and /resource_providers. I think we should,
but the immediate need is on /allocation_candidates.

There's some proposed code to get the latter started:


## Shared Resource Providers

Support for shared resource providers is "built in" to the
/allocation_candidates concept and one of the drivers for having it.

There was a thread on the dev list recently about using them with
custom resource classes which may be instructive:


## Nested Resource Providers

Work continues on nested resource providers.


The need with these is simply more review, but they are behind
claims in priority.

## Docs

Lots of placement-related api docs have merged or are in progress:


Setting up the official publishing job for the api ref is on hold
until the content has been migrated to the locations specified by the
docs migration that is currently in progress:


Some changes have been proposed to document the scheduler's
workflow, including visual aids, starting at:


# Other Code/Specs

* https://review.openstack.org/#/c/472378/
     A proposed fix to using multiple config locations with the
     placement wsgi app. There's some active discussion on whether the
     solution in mind is the right solution, or even whether the bug is
     a bug (it is!).

* https://review.openstack.org/#/c/470578/
     Add functional test for local delete allocations

* https://review.openstack.org/#/c/427200/
        Add a status check for legacy filters in nova-status.

* https://review.openstack.org/#/c/469048/
      Provide more information about installing placement

* https://review.openstack.org/#/c/468928/
      Disambiguate resource provider conflict message

* https://review.openstack.org/#/c/468797/
      Spec for requesting traits in flavors

* https://review.openstack.org/#/c/480379/
    ensure shared RP maps with correct root RP
    (Some discussion on this one what the goal is and whether the
    approach is the right one.)

* https://review.openstack.org/#/c/483506/
   Call _update fewer times in the resource tracer

* https://review.openstack.org/#/c/483460/
   Retry resource provider registration when session's service
   catalog does not have placement

* https://review.openstack.org/#/c/452006/
   A functional test to confirm that migration between two different
   cells is not allowed. Included here because it uses the
   PlacementFixture and may be experiencing the bug that
   https://review.openstack.org/#/c/483564/ is trying to fix.

# End

Thanks for reading this far. Now please go review some of the things
linked above. Your prize is a reservation on a delicate thrown
porcelain cup or bowl, hand made in Cornwall after I retire.

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

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