I already started a stand alone eureka service and a @EnableDiscoveryClient annotated spring boot admin server. And the admin server was already registered in the eureka successfully. Now question is how to register a spring boot application to the admin server through eureka?
PS: without eureka, we need to add config: spring.boot.admin.url=http://localhost:8080 in the admin client to register the client to the admin server.
If your client apps are regular eureka apps they should show up in the admin server. There is also a short section on this in the docs: http://codecentric.github.io/spring-boot-admin/1.4.3/#discover-clients-via-spring-cloud-discovery