Comment 18 for bug 1735407

Reviewed: https://review.openstack.org/525242
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=edeeaf9102eccb78f1a2555c7e18c3d706f07639
Submitter: Zuul
Branch: master

commit edeeaf9102eccb78f1a2555c7e18c3d706f07639
Author: Balazs Gibizer <email address hidden>
Date: Mon Dec 4 16:18:30 2017 +0100

    Add late server group policy check to rebuild

    The affinity and anti-affinity server group policy is enforced by the
    scheduler but two parallel scheduling could cause that such policy is
    violated. During instance boot a late policy check was performed in
    the compute manager to prevent this. This check was missing in case
    of rebuild. Therefore two parallel evacuate command could cause that
    the server group policy is violated. This patch introduces the late
    policy check to rebuild to prevent such situation. When the violation
    is detected during boot a re-scheduling happens. However the rebuild
    action does not have the re-scheduling implementation so in this case
    the rebuild will fail and the evacuation needs to be retried by the
    user. Still this is better than allowing a parallel evacuation to
    break the server group affinity policy.

    To make the late policy check possible in the compute/manager the
    rebuild_instance compute RPC call was extended with a request_spec
    parameter.

    Co-Authored-By: Richard Zsarnoczai <email address hidden>

    Change-Id: I752617066bb2167b49239ab9d17b0c89754a3e12
    Closes-Bug: #1735407