Comment 9 for bug 1895696

Reviewed: https://review.opendev.org/752090
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=f9b67893acf94c06fd41be36b80b99788dc77e48
Submitter: Zuul
Branch: master

commit f9b67893acf94c06fd41be36b80b99788dc77e48
Author: Lee Yarwood <email address hidden>
Date: Tue Sep 15 18:17:04 2020 +0100

    compute: Skip cinder_encryption_key_id check when booting from volume

    Idf84ccff254d26fa13473fe9741ddac21cbcf321 added this check in order for
    Nova to avoid booting encrypted images created by Cinder as there is
    currently no support for using such images (rotating keys etc).

    The check however missed the slightly convoluted use case where this
    image property is found against a volume after the volume in question is
    created using an encrypted image created by cinder from an encrypted
    volume. In other words:

    - Cinder creates an encrypted volume A
    - Glance creates an encrypted image A from volume A
    - Cinder creates an encrypted volume B from image A
    - Nova attempts to boot an instance using volume B

    Note that Nova may request the creation of volume B or a user could also
    do this directly through Cinder.

    As such this change simply ensures that the instance isn't booting from
    a volume when preforming the check as it is only valid when booting from
    an image.

    Closes-Bug: #1895696
    Change-Id: Ic92cab7362fa25050e5bbef5c3e360108365b5c7