oslo messaging notifications to a separate RabbitMQ server

[masterpe]

Description
===========
In the oslo_messaging_notifications we use a standalone RabbitMQ server for the messagingv2 notifications. When this server is offline the reties to send the message is indefinite.

This resulted in that Nova API was not reacting anymore.

Steps to reproduce
==================
Shutdown the RabbitMQ server, this result in that the Nova messagingv2 is trying to send the messaging indefinite and the Nova API was not responding any more.

Expected result
===============
Nova API will function without any problems and that the RPC messages will continue to send over the main RabbitMQ server.

Actual result
=============
Nova API was not responding

Environment
===========
We use Openstack Ussuri and using 21.2.1. This got installed using OSA 21.2.6

root@tctrko2-nova-api-container-e695ebea:~# /openstack/venvs/nova-21.2.6/bin/nova-manage --version
21.2.1

Logs & Configs
==============
nova.conf
[DEFAULT]
transport_url = rabbit://nova:ww@192.168.0.235:5671,nova:ww@192.168.0.220:5671,nova:ww@192.168.0.22:5671//nova?ssl=1

[oslo_messaging_notifications]
topics = notifications
driver = messagingv2
transport_url = rabbit://user2:ww@192.168.0.17:5672//?ssl=0

[Mohammed Naser (mnaser)]

I did a bunch of research and I believe this is a duplicate of the following Launchpad bug: https://bugs.launchpad.net/nova/+bug/1917645