Then the Spring Cloud Config Server will retrieve the latest configuration property changes from the backend systems and publish the refresh event to the Spring Cloud Bus. This refresh event is published with Spring Cloud Stream.

All the distributed application services will connect to Spring Cloud Bus and will listen for the refresh event published by the Spring Cloud Config Server. The Spring Cloud Bus will broadcast the refresh event across all connected application services. Therefore it is guaranteed that the the published refresh event will be received by every distributed service (Config Client) that is connected to the Spring Cloud Bus.

Every Config Client (application service) has the Spring Boot Actuator in its classpath. Therefore all the application services can accept and handle the refresh event with no issue. Then all the beans annotated with @RefreshScope will be refreshed and the properties will be re-fetched. That means the Config Client will communicate with Config Server to retrieve the latest configuration properties for the related to the annotated beans.

https://medium.com/swlh/spring-cloud-config-bus-auto-refresh-properties-for-clients-d18fa4c036cb