Comment 9 for bug 1734872

Reviewed: https://review.opendev.org/665214
Committed: https://git.openstack.org/cgit/openstack/kolla-ansible/commit/?id=f6cfee3201d0067ee500dd507924038315ac6efd
Submitter: Zuul
Branch: stable/queens

commit f6cfee3201d0067ee500dd507924038315ac6efd
Author: Pierre Riteau <email address hidden>
Date: Thu Jun 6 18:10:06 2019 +0100

    Stop duplicating Nova cells

    Check if a base Nova cell already exists before calling `nova-manage
    cell_v2 create_cell`, which would otherwise create a duplicate cell when
    the transport URL or database connection change.

    If a base cell already exists but the connection values have changed, we
    now call `nova-manage cell_v2 update_cell` instead. This is only
    possible if a duplicate cell has not yet been created. If one already
    exists, we print a warning inviting the operator to perform a manual
    cleanup. We don't use a hard fail to avoid an abrupt change of behavior
    if this is backported to stable branches.

    Change-Id: I7841ce0cff08e315fd7761d84e1e681b1a00d43e
    Closes-Bug: #1734872
    (cherry picked from commit 19b8dbe460315c5da23c33aa57c967d75d7f2018)