The application for that guide is a Spring Boot Application.
Add a file application.properties to src/main/resources.
You can then configure rabbitmq properties according to the Spring Boot Documentation – scroll down to the rabbitmq properties…
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spring.rabbitmq.host=localhost # RabbitMQ host.
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spring.rabbitmq.password= # Login to authenticate against the broker.
spring.rabbitmq.port=5672 # RabbitMQ port.
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spring.rabbitmq.username= # Login user to authenticate to the broker.
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To connect to a cluster, use
spring.rabbitmq.addresses= # Comma-separated list of addresses to which the client should connect.
e.g. server1:5672,server2:5672.
If you don’t want to use boot auto configuration, declare a CachingConnectionFactory @Bean yourself and configure it as desired.