Currently in tripleo we have a parameter called NotificationDriver which is defined as follows:
NotificationDriver:
type: string
default: 'messagingv2'
description: Driver or drivers to handle sending notifications.
The problem is that it is impossible to set multiple driver notifications which is desired from time to time. Note that oslo messaging expects multiple drivers to be specified in separate and multiple 'driver=foo\ndriver=bar' lines and *not* in a single 'driver=foo,bar' line [1].
The reason this is not possible is many-fold:
A) Most puppet modules (aodh, cinder, glance, heat, keystone) use the traditional ini puppet backend that does not allow for multiple lines of the same key within the same section.
B) puppet-oslo defines the oslo::messaging::notifications::driver parameter as list but then it actually converts it into a comma separated string:
https://github.com/openstack/puppet-oslo/blob/master/manifests/messaging/notifications.pp#L10
C) Tripleo Heat templates are always passing the notification_driver hiera keys as strings
[1] From https://docs.openstack.org/oslo.config/queens/configuration/format.html we have the following:
multi valued (MultiStrOpt)
A multi-valued option is a string value and can be given more than once, all values will be used.
# Driver or drivers to handle sending notifications. (multi valued)
notification_driver = nova.openstack.common.notifier.rpc_notifier
notification_driver = ceilometer.compute.nova_notifier
A)
https:/
https:/
https:/
https:/
https:/
B)
https:/
C)
https:/