openstack-manuals/doc/install-guide/source/environment-messaging.rst

Message queue

OpenStack uses a message queue to coordinate operations and status information among services. The message queue service typically runs on the controller node. OpenStack supports several message queue services including RabbitMQ and Qpid. However, most distributions that package OpenStack support a particular message queue service. This guide implements the RabbitMQ message queue service because most distributions support it. If you prefer to implement a different message queue service, consult the documentation associated with it.

The message queue runs on the controller node.

environment-messaging-*