yahoo-eng-team team mailing list archive

[Eric Fried <efried@xxxxxxxxxx>]

Public bug reported:

Today the report client makes assumptions about how resource provider
generation is calculated by the placement service.  Specifically, that
it starts at zero [1], and that it increases by 1 when the provider's
inventory is deleted [2].

While these assumptions happen to be true today [3], they are not a
documented part of the placement API.  Which either means we need to
document this behavior; or clients should not be relying on it.

[1] https://github.com/openstack/nova/blob/b214dfc41928d9e05199263301f8e5b23555c170/nova/scheduler/client/report.py#L552
[2] https://github.com/openstack/nova/blob/b214dfc41928d9e05199263301f8e5b23555c170/nova/scheduler/client/report.py#L927
[3] The latter more broadly stated as "increases by 1 when anything about the provider changes" - except we have a known hole for aggregates (see https://blueprints.launchpad.net/nova/+spec/placement-aggregate-generation)

** Affects: nova
     Importance: Undecided
         Status: New


** Tags: placement

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https://bugs.launchpad.net/bugs/1746075

Title:
  Report client placement cache consistency is broken

Status in OpenStack Compute (nova):
  New

Bug description:
  Today the report client makes assumptions about how resource provider
  generation is calculated by the placement service.  Specifically, that
  it starts at zero [1], and that it increases by 1 when the provider's
  inventory is deleted [2].

  While these assumptions happen to be true today [3], they are not a
  documented part of the placement API.  Which either means we need to
  document this behavior; or clients should not be relying on it.

  [1] https://github.com/openstack/nova/blob/b214dfc41928d9e05199263301f8e5b23555c170/nova/scheduler/client/report.py#L552
  [2] https://github.com/openstack/nova/blob/b214dfc41928d9e05199263301f8e5b23555c170/nova/scheduler/client/report.py#L927
  [3] The latter more broadly stated as "increases by 1 when anything about the provider changes" - except we have a known hole for aggregates (see https://blueprints.launchpad.net/nova/+spec/placement-aggregate-generation)

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