--- prelude: > RabbitMQ Quorum Queues are enabled by default along with other significant improvements to oslo.messaging, like Queue Manager, Transient Queues to use Quorum, usage of Stream Queues for fanout. You can check more details for these options in `oslo.messaging release notes `_ features: - | Implemented new variables to control new oslo.messaging behaviour: - oslomsg_rabbit_stream_fanout: Enabled if ``oslomsg_rabbit_quorum_queues`` is also set to `True` - oslomsg_rabbit_transient_quorum_queues: Enabled if ``oslomsg_rabbit_stream_fanout`` is `True` - oslomsg_rabbit_qos_prefetch_count: Must be set to a positive value if ``oslomsg_rabbit_stream_fanout`` is `True` - oslomsg_rabbit_queue_manager: Disabled by default. There is a known issue of missing [oslo_concurrency]/lock_path defenition in some service configs, which is required for QManager SHM locking process. Each service also has corresponsive variables prefixed with service name, like ``_oslomsg_rabbit_stream_fanout`` to control them separately. upgrade: - | With enablement of RabbitMQ Quorum Queues by default, all vhosts will be re-created and re-named without leading slash ('/'). For instance, `/nova` vhost will be renamed to `nova`. This might affect configured monitoring alert rules or statistics gathering. Renaming process will also lead for prolonged downtime of services during upgrade which will last from vhost renaming until service role execution completition. This might be especially important for services like Nova and Neutron where role runtime may take a while to cover all hosts. You can disable usage of Quorum Queues and use previous default of HA Queues by defining ``oslomsg_rabbit_quorum_queues: False`` in your user_variables.yml Please check `RabbitMQ maintenance `_ documentation for more infromation on how to switch between these 2 modes with reduced downtime.