Implement Zookeeper Service Discovery and Load Balancing with Spring Cloud

Environment: Spring Boot 2.3.9 + Spring Cloud Hoxton.SR8.

Reference Zookeeper installation and configuration (see related tutorial).

Service Provider

Dependency

<properties>
  <spring-cloud.version>Hoxton.SR8</spring-cloud.version>
</properties>
<dependencies>
  <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
  </dependency>
</dependencies>
<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-dependencies</artifactId>
      <version>${spring-cloud.version}</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

bootstrap.yml configuration

spring:
  cloud:
    zookeeper:
      connectString: localhost:2181,localhost:2182,localhost:2183
      connectionTimeout: 3000

This config connects the application to Zookeeper on startup.

application.yml configuration

server:
  port: 8081
---
spring:
  application:
    name: zk-client
---
spring:
  cloud:
    loadbalancer:
      ribbon:
        enabled: false

Ribbon is disabled because it is deprecated; Spring Cloud LoadBalancer replaces it.

Test endpoint

@RestController
@RequestMapping("/producer")
public class ProducerController {
    @Value("${server.port}")
    private Integer port;
    @GetMapping("")
    public String serviceUrl() {
        return "我的端口是" + port;
    }
}

Two instances are started on ports 8080 and 8081. After launch, both register in Zookeeper (see screenshots).

Service Consumer

Dependencies and configuration

Same as provider except spring.application.name=zk-consumer.

RestTemplate configuration

@Configuration
public class WebConfig {
    @Resource
    private RestTemplateBuilder builder;
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return builder.build();
    }
}

The @LoadBalanced annotation enables client‑side load balancing.

Test endpoint to list provider instances

@RestController
@RequestMapping("/balanced")
public class BalancedController {
    @Resource
    private DiscoveryClient discoveryClient;
    @GetMapping("/get")
    public Object serviceUrl() {
        List<ServiceInstance> list = discoveryClient.getInstances("zk-client");
        return list;
    }
}

This endpoint returns all instances of the service named zk-client.

Invoke provider via RestTemplate

@Resource
private RestTemplate restTemplate;
@GetMapping("/producer")
public Object invokeProducer() {
    return restTemplate.getForObject("http://zk-client/producer", String.class);
}

The host part uses the service name ( zk-client) instead of a fixed URL, allowing load balancing.

Running the consumer shows alternating responses from ports 8080 and 8081, confirming successful load balancing.

All steps complete.