The last post illustrated setting up a basic RabbitMQ federation. That post used the basic guest account when connecting similarly named virtual hosts on the downstream to the upstream. It's also possible to use different users and connect different virtual hosts.
The picture below is a shot of the connections on the upstream broker. It shows that there is a connection to the FederationDemo virtual host. You can see that it is the guest user which is connected.
The credentials are specified in the URI used when creating the upstream. Just below the 'Add new upstream' panel is a panel with different examples. These show how use various credentials.
When different credentials are supplied in the URI, the federation is created with a different user. It holds that the user must have access to the upstream virtual host. Thus, an upstream created with a URI like amqp://FederatedUser:user@RABBIT/FederationDemo opens the following connection:
Connecting with different credentials is easy. You can specify a different user, or a different virtual host.