Comment 3 for bug 1775075

Reviewed: https://review.openstack.org/572213
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=c7d87f6691bbc39daca918729b769cc2d2000abd
Submitter: Zuul
Branch: stable/queens

commit c7d87f6691bbc39daca918729b769cc2d2000abd
Author: Lee Yarwood <email address hidden>
Date: Mon Jun 4 22:12:18 2018 +0100

    Allow cinderv2 endpoints within the request context catalog

    This partially reverts commit a03976ee892333720b2227f607a5ddbb77163fea.

    During a P to Q upgrade it is common to have the control services
    upgraded to Q ahead of the computes. During this time the Q n-api
    services will provide request contexts over the wire to these P computes
    where the service catalog held within does not contain any cinderv2 type
    endpoints, as cinderv2 support has been removed from Nova in Q.

    This becomes a problem if the P computes are specifically looking for a
    cinderv2 type endpoint via [cinder]catalog_info within nova.conf. For
    example with TripleO deployed Pike environments this has a default value
    of 'volumev2:cinderv2:internalURL'.

    This change ensures cinderv2 type endpoints are still provided by Queens
    n-api control services to Pike computes during an upgrade. This is only
    required on stable/queens as we only support N-1 running computes during
    an upgrade and so we don't need to land anything in R to support P
    computes.

    Closes-bug: #1775075
    Change-Id: I45299df2bf095c12bfce5b1ac3e5460a11dd0131