Comment 2 for bug 1774401

Reviewed: https://review.openstack.org/628152
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=a017ecac9f2ea9353f9cf5829490c20ee875660d
Submitter: Zuul
Branch: master

commit a017ecac9f2ea9353f9cf5829490c20ee875660d
Author: Harald Jensås <email address hidden>
Date: Thu Jan 3 11:38:22 2019 +0100

    Fall back public_virtual_ip to ctlplane if External net not present

    public_virtual_ip previously required the External network to be
    present in networks data. Add a conditional to use the VIP on the
    ctlplane if the External network is not in networks data.

    Closes-Bug: #1774401
    Change-Id: Ie6c3d7124d11ee89788b432da39df16f031fcf12