Comment 9 for bug 1746483

Reviewed: https://review.openstack.org/543263
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=0a7427dc58eeb271646a962604106e0e84b870b6
Submitter: Zuul
Branch: master

commit 0a7427dc58eeb271646a962604106e0e84b870b6
Author: Matt Riedemann <email address hidden>
Date: Sun Feb 11 16:58:02 2018 -0500

    Handle volume-backed instances in IsolatedHostsFilter

    The RequestSpec.image object for a volume-backed instance will
    not have the 'id' attribute set because the
    nova.utils.get_image_metadata_from_volume() method doesn't convert
    the volume['volume_image_metadata']['image_id'] into the ImageMeta.id
    field. It is unclear if there are intentional reasons for omitting
    this information, but the IsolatedHostsFilter has just never supported
    filtering for volume-backed instances based on a provided image id.

    The logic within the filter depends on the
    restrict_isolated_hosts_to_isolated_images config option, which
    defaults to True. When True, a volume-backed instance will not be
    put on an isolated host. When False, a volume-backed instance can
    go on any host, isolated or not.

    Again, it's unclear if we should actually be filtering volume-backed
    servers using the image_id from the volume_image_metadata or not,
    but it's not what we've historically done so this change simply
    fixes the regression bug.

    Change-Id: Ieb8abb1a3f04ce008f9617e051e4d720dbe6917a
    Closes-Bug: #1746483