how to build a feign client by coding

i havethe eureka server http://127.0.0.1:8761,http://127.0.0.1:8762,http://127.0.0.1:8763,some service named app1,app2,,,appn,how can i get the service in appx, i can't use @FeignClient because the appx is uncertain,
the eureka server is configured in the application.yml 