yahoo-eng-team team mailing list archive

[Matt Riedemann <mriedem.os@xxxxxxxxx>]

** Also affects: nova/rocky
   Importance: Undecided
       Status: New

** Changed in: nova/rocky
       Status: New => In Progress

** Changed in: nova/rocky
   Importance: Undecided => Medium

** Changed in: nova/rocky
     Assignee: (unassigned) => Matt Riedemann (mriedem)

-- 
You received this bug notification because you are a member of Yahoo!
Engineering Team, which is subscribed to OpenStack Compute (nova).
https://bugs.launchpad.net/bugs/1785339

Title:
  RequestSpec.flavor is not reverted on resize revert

Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Compute (nova) ocata series:
  Confirmed
Status in OpenStack Compute (nova) pike series:
  Confirmed
Status in OpenStack Compute (nova) queens series:
  In Progress
Status in OpenStack Compute (nova) rocky series:
  In Progress

Bug description:
  When we resize a server, we update the RequestSpec.flavor because for
  later move operations of the server, the RequestSpec is what gets
  passed to the scheduler, so naturally we need the RequestSpec.flavor
  to match the instance.flavor after the instance is resized. That
  happens here:

  https://github.com/openstack/nova/blob/4c37ff72e5446c835a48d569dd5a1416fcd36c71/nova/conductor/manager.py#L313

  https://github.com/openstack/nova/blob/4c37ff72e5446c835a48d569dd5a1416fcd36c71/nova/conductor/manager.py#L352

  However, if the resize is reverted, we don't actually rollback the
  RequestSpec.flavor to the previously flavor (instance.old_flavor):

  https://github.com/openstack/nova/blob/4c37ff72e5446c835a48d569dd5a1416fcd36c71/nova/compute/api.py#L3322

  So consider this scenario:

  1. create server with flavor 1
  2. resize to server 2 (VERIFY_RESIZE status); at this point the RequestSpec.flavor is 2
  3. revert the resize
  4. live migrate, shelve/unshelve, evacuate or cold migrate the server - the request spec passed to the scheduler will have flavor 2 rather than flavor 1 which could cause misleading scheduling failures, e.g. if flavor 2 is bigger than flavor 1 and there is no capacity for flavor 2 on any hosts, the scheduler would raise NoValidHost.

To manage notifications about this bug go to:
https://bugs.launchpad.net/nova/+bug/1785339/+subscriptions