RabbitMQ is a message broker written in Erlang. It is currently the default provider of message queues in Kolla Ansible deployments.

Passing arguments to RabbitMQ server’s Erlang VM

Erlang programs run in Erlang VM (virtual machine) and use Erlang runtime. Erlang VM can be configured.

Kolla Ansible makes it possible to pass arguments to the Erlang VM via the usage of rabbitmq_server_additional_erl_args variable. The contents of it are appended to RABBITMQ_SERVER_ADDITIONAL_ERL_ARGS environment variable passed to RabbitMQ server startup script. Kolla Ansible already configures RabbitMQ server for IPv6 (if necessary). Any argument can be passed there as documented in https://www.rabbitmq.com/runtime.html