Before you can join a node to a cluster, you must first stop the RabbitMQ application and reset the node. This can be done with the rabbitmqctl stop_app and rabbitmqctl reset commands.

IMPORTANT

Be aware that reset will remove all resources and data on the node.

rabbitmqctl stop_app
rabbitmqctl reset

Then the rabbitmqctl join_cluster command can be used.

AVOID TROUBLE

The Erlang cookie on each node must be identical. Typically, the file that contains the Erlang cookie is /var/lib/rabbitmq/.erlang.cookie. The RABBITMQ_ERLANG_COOKIE variable can be used to define the Erlang cookie on each RabbitMQ node.

Let's say this command is run on the node with hostname rabbit2.example.com. This command will create a cluster that contains both rabbit1.example.com and rabbit2.example.com.

rabbitmqctl join_cluster rabbit@rabbit1.example.com