SERVER_PORT=9999 mvn spring-boot:run

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>

server.port= 8090
spring.application.name = server

@RestController
@SpringBootApplication
public class ServerApplication {

    @Autowired
    private ServerProperties serverProperties;

    private static Logger log = LoggerFactory.getLogger(ServerApplication.class);

    public static void main(String[] args) {
        SpringApplication.run(ServerApplication.class, args);
    }

    @GetMapping("/greeting")
    public String greet() {
        log.info("Access /greeting");

        List<String> greetings = Arrays.asList("Hi there", "Greetings", "Salutations");
        Random rand = new Random();

        int randomNum = rand.nextInt(greetings.size());
        return greetings.get(randomNum) + serverProperties.getPort();
    }


    @GetMapping("/")
    public String home() {
        log.info("Access /");
        return "Hi!";
    }
}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>

server.port= 8888
spring.application.name = client

@SpringBootApplication
@RestController
public class ClientApplication {

    private final WebClient.Builder loadBalancedWebClientBuilder;
    private final ReactorLoadBalancerExchangeFilterFunction lbFunction;


    public ClientApplication(WebClient.Builder webClientBuilder,
                           ReactorLoadBalancerExchangeFilterFunction lbFunction) {
        this.loadBalancedWebClientBuilder = webClientBuilder;
        this.lbFunction = lbFunction;
    }

    public static void main(String[] args) {
        SpringApplication.run(ClientApplication.class, args);
    }


    private String serverName = "server";

    @RequestMapping("/hi")
    public Mono<String> hi(@RequestParam(value = "name", defaultValue = "Mary") String name) {
        return loadBalancedWebClientBuilder.build().get().uri("http://"+serverName+"/greeting")
                .retrieve().bodyToMono(String.class)
                .map(greeting -> String.format("%s, %s!", greeting, name));
    }

    @RequestMapping("/hello")
    public Mono<String> hello(@RequestParam(value = "name", defaultValue = "John") String name) {
        return WebClient.builder()
                .filter(lbFunction)
                .build().get().uri("http://"+serverName+"/greeting")
                .retrieve().bodyToMono(String.class)
                .map(greeting -> String.format("%s, %s!", greeting, name));
    }
}

@Configuration
public class ClientConfig {

    @Bean
    @Primary
    ServiceInstanceListSupplier serviceInstanceListSupplier() {
        return new DemoServiceInstanceListSuppler("server");
    }

}

@Configuration
@LoadBalancerClient(name = "client", configuration = ClientConfig.class)
public class WebClientConfig {

    @LoadBalanced
    @Bean
    WebClient.Builder webClientBuilder() {
        return WebClient.builder();
    }

}

lass DemoServiceInstanceListSuppler implements ServiceInstanceListSupplier {

    private final String serviceId;

    DemoServiceInstanceListSuppler(String serviceId) {
        this.serviceId = serviceId;
    }

    @Override
    public String getServiceId() {
        return serviceId;
    }

    @Override
    public Flux<List<ServiceInstance>> get() {
        return Flux.just(Arrays
                .asList(new DefaultServiceInstance(serviceId + "1", serviceId, "localhost", 8090, false),
                        new DefaultServiceInstance(serviceId + "2", serviceId, "localhost", 8092, false),
                        new DefaultServiceInstance(serviceId + "3", serviceId, "localhost", 8093, false))
        );
    }
}