OpenStack projects use an open standard for messaging middleware known as AMQP. This messaging middleware enables the OpenStack services that run on multiple servers to talk to each other. OpenStack Oslo RPC supports three implementations of AMQP: RabbitMQ, Qpid, and ZeroMQ.

OpenStack Oslo RPC uses RabbitMQ by default. Use these options to configure the RabbitMQ message system. The rpc_backend option is optional as long as RabbitMQ is the default messaging system. However, if it is included in the configuration, you must set it to heat.openstack.common.rpc.impl_kombu. rpc_backend = heat.openstack.common.rpc.impl_kombu Use these options to configure the RabbitMQ messaging system. You can configure messaging communication for different installation scenarios, tune retries for RabbitMQ, and define the size of the RPC thread pool. To monitor notifications through RabbitMQ, you must set the notification_driver option to heat.openstack.common.notifier.rpc_notifier in the heat.conf file:

Use these options to configure the Qpid messaging system for OpenStack Oslo RPC. Qpid is not the default messaging system, so you must enable it by setting the rpc_backend option in the heat.conf file: rpc_backend=heat.openstack.common.rpc.impl_qpid This critical option points the compute nodes to the Qpid broker (server). Set the qpid_hostname option to the host name where the broker runs in the heat.conf file. The qpid_hostname option accepts a host name or IP address value. qpid_hostname = hostname.example.com If the Qpid broker listens on a port other than the AMQP default of 5672, you must set the qpid_port option to that value: qpid_port = 12345 If you configure the Qpid broker to require authentication, you must add a user name and password to the configuration: qpid_username = username qpid_password = password By default, TCP is used as the transport. To enable SSL, set the qpid_protocol option: qpid_protocol = ssl Use these additional options to configure the Qpid messaging driver for OpenStack Oslo RPC. These options are used infrequently.

Use these options to configure the ZeroMQ messaging system for OpenStack Oslo RPC. ZeroMQ is not the default messaging system, so you must enable it by setting the rpc_backend option in the heat.conf file:

Use these common options to configure the RabbitMQ, Qpid, and ZeroMq messaging drivers: