Spring Cloud step-by-step (part 5) – Cloudly Tech

In previous blog post I showed you how to invoke other services using EurekaClient , but there is a simpler way.
RestTemplate is smart enough to resolve service URI from Eureka server itself.
Ribbon is a client-side load balancer and SpringTemplate supports it by simply adding one annotation: @LoadBalanced .
Let’s create version 2 of Rental Service controller which will look this way:
@RestController
@RequestMapping(path = "/v2")
public class RentalControllerV2 {
    protected String serviceUrl = "http://PRICING-SERVICE";
    private final RestTemplate restTemplate;
    public RentalControllerV2(@Qualifier("ribbon-template") RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    @RequestMapping(path = "/rentals/{id}/charges", method = RequestMethod.GET)
    public ResponseEntity getPossibleCharges(@PathVariable("id") String id) {
        ZonedDateTime startTime = ZonedDateTime.now();
        ZonedDateTime endTime = startTime.plus(2, ChronoUnit.DAYS);
        HttpEntity<PriceRequest> request = new HttpEntity<>(
                new PriceRequest("vip", startTime, endTime)
        PriceResponse response = restTemplate.postForObject(serviceUrl + "/v1/prices", request, PriceResponse.class);
        return new ResponseEntity<>(new RentalChargesResponse(response.getPrice()), HttpStatus.OK);
To enable Ribbon we have to add this property in bootstrap.yaml or application.yaml
ribbon:
  http:
    client:
      enabled: true
In the controller above I am injecting RestTemplate as a bean named ribbon-template.
This is because I wanted to leave two RestTemplate beans in the application: one which we use in version 1 controller with native EurekaClient API and another in version 2 controller which is load-balanced RestTemplate.
This is how my beans configuration looks like in main class:
@Bean
public RestTemplate restTemplate() {
	return new RestTemplate();
@Bean("ribbon-template")
@LoadBalanced
public RestTemplate restTemplateWithRibbon() {
	return new RestTemplate();
And that’s it. Start the application and invoke endpoint:
curl localhost:8080/v2/rentals/1/charges
You will see in logs how Spring is resolving Rental Service URL from service name:
2018-06-29 01:11:58.027  INFO 18934 --- [nio-8080-exec-1] c.netflix.config.ChainedDynamicProperty  : Flipping property: PRICING-SERVICE.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2018-06-29 01:11:58.048  INFO 18934 --- [nio-8080-exec-1] c.n.u.concurrent.ShutdownEnabledTimer    : Shutdown hook installed for: NFLoadBalancer-PingTimer-PRICING-SERVICE
2018-06-29 01:11:58.067  INFO 18934 --- [nio-8080-exec-1] c.netflix.loadbalancer.BaseLoadBalancer  : Client: PRICING-SERVICE instantiated a LoadBalancer: DynamicServerListLoadBalancer:{NFLoadBalancer:name=PRICING-SERVICE,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
2018-06-29 01:11:58.072  INFO 18934 --- [nio-8080-exec-1] c.n.l.DynamicServerListLoadBalancer      : Using serverListUpdater PollingServerListUpdater
2018-06-29 01:11:58.089  INFO 18934 --- [nio-8080-exec-1] c.netflix.config.ChainedDynamicProperty  : Flipping property: PRICING-SERVICE.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
2018-06-29 01:11:58.090  INFO 18934 --- [nio-8080-exec-1] c.n.l.DynamicServerListLoadBalancer      : DynamicServerListLoadBalancer for client PRICING-SERVICE initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=PRICING-SERVICE,current list of Servers=[192.168.43.107:46579],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone;	Instance count:1;	Active connections count: 0;	Circuit breaker tripped count: 0;	Active connections per server: 0.0;]
},Server stats: [[Server:192.168.43.107:46579;	Zone:defaultZone;	Total Requests:0;	Successive connection failure:0;	Total blackout seconds:0;	Last connection made:Thu Jan 01 01:00:00 CET 1970;	First connection made: Thu Jan 01 01:00:00 CET 1970;	Active Connections:0;	total failure count in last (1000) msecs:0;	average resp time:0.0;	90 percentile resp time:0.0;	95 percentile resp time:0.0;	min resp time:0.0;	max resp time:0.0;	stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@fcc5a3d
2018-06-29 01:11:58.131  INFO 18934 --- [nio-8080-exec-1] com.netflix.http4.ConnectionPoolCleaner  : Initializing ConnectionPoolCleaner for NFHttpClient:PRICING-SERVICE
2018-06-29 01:11:59.075  INFO 18934 --- [erListUpdater-0] c.netflix.config.ChainedDynamicProperty  : Flipping property: PRICING-SERVICE.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647