Comment 2 for bug 1520613

It heppens because of :
"No valid host was found. There are not enough hosts available."

There are no hypervisors in the openstack env. It's because computes are not able to connect to rabbitmq:

<183>Nov 27 16:04:20 node-3 nova-compute: Received recoverable error from kombu:
<179>Nov 27 16:04:20 node-3 nova-compute: AMQP server on 10.200.240.1:5673 is unreachable: timed out. Trying again in 6 seconds.

Messaging traffic has been moved to br-messaging:
10.200.240.0/24 dev br-messaging proto kernel scope link src 10.200.240.1

But on controller side connection to rabbitmq are blocked by firewall, only management network is allowed (note zero counters):

    0 0 ACCEPT tcp -- * * 10.109.6.0/24 0.0.0.0/0 multiport ports 4369,5672,5673,41055 /* 106 rabbitmq from 10.109.6.0/24 */

But not mgmt/messaging net role.