Comment 59 for bug 1664931

Reviewed: https://review.openstack.org/519672
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=9e2d63da94db63d97bd02e373bfc53d95808b833
Submitter: Zuul
Branch: stable/pike

commit 9e2d63da94db63d97bd02e373bfc53d95808b833
Author: Matt Riedemann <email address hidden>
Date: Fri Oct 27 16:03:15 2017 -0400

    Validate new image via scheduler during rebuild

    During a rebuild we bypass the scheduler because we are
    always rebuilding the instance on the same host it's already
    on. However, we allow passing a new image during rebuild
    and that new image needs to be validated to work with the
    instance host by running it through the scheduler filters,
    like the ImagePropertiesFilter. Otherwise the new image
    could violate constraints placed on the host by the admin.

    This change checks to see if there is a new image provided
    and if so, modifies the request spec passed to the scheduler
    so that the new image is validated all while restricting
    the scheduler to still pick the same host that the instance
    is running on. If the image is not valid for the host, the
    scheduler will raise NoValidHost and the rebuild stops.

    A functional test is added to show the recreate of the bug
    and that we probably stop the rebuild now in conductor by
    calling the scheduler to validate the image.

    Co-Authored-By: Sylvain Bauza <email address hidden>

    Closes-Bug: #1664931

    NOTE(mriedem): The backport has to explicitly use the
    filter scheduler in the test setup and move the start of
    the compute service to after the placement fixture usage.
    This is because cc833359870d3962326c35094adea2f525ec8141
    is not in stable/pike.

    Change-Id: I11746d1ea996a0f18b7c54b4c9c21df58cc4714b
    (cherry picked from commit 984dd8ad6add4523d93c7ce5a666a32233e02e34)