RabbitMQ with High Availability

By default, queues within a RabbitMQ cluster are located on a single node (the node on which they were first declared). This is in contrast to exchanges and bindings, which can always be considered to be on all nodes. Queues can optionally be made mirrored across multiple nodes.

Each mirrored queue consists of onemaster and one or more slaves, with the oldest slave being promoted to the new master if the old master disappears for any reason.

Messages published to the queue are replicated to all slaves. Consumers are connected to the master regardless of which node they connect to, with slaves dropping messages that have been acknowledged at the master. Queue mirroring therefore enhances availability, but does not distribute load across nodes (all participating nodes each do all the work).

This solution requires a RabbitMQ cluster, which means that it will not cope seamlessly with network partitions within the cluster and, for that reason, is not recommended for use across a WAN (though of course, clients can still connect from as near and as far as needed).