title: What is the meaning of the vhost in RabbitMQ?
body: <p>When I set permissions to the rabbitmq user, there is output the <code>vhost</code>: </p>
  
  <pre><code>[root@ha-node1 my.cnf.d]# rabbitmqctl set_permissions openstack ".*" ".*" ".*" 
  Setting permissions for user "openstack" in vhost "/" ...
  </code></pre>
  
  <p>What is the meaning of the <code>vhost</code> when I set permission, and what function does it have?</p>