spring cloud client load balancing - Ribbon

Spring Cloud Ribbon is based on HTTP and TCP client load balancing tool, Netflix Ribbon-based implementation, Ribbon, unlike registry, so need to deploy a separate gateway, which is integrated directly into Service in as a tool. Feign to be mentioned later which also integrates Ribbon.

1, manually set up a client load balancing

Ready to work:

• Preparation of a peer1, peer2 configuration center composed of
• Preparation of a service-1 (8091), service-1 (8092) of the server cluster configuration
• Prepare a Ribbon client

Add pom-dependent

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

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Ribbon client, using @EnableDiscoveryClient registered with the Eureka:

@SpringBootApplication 
@EnableDiscoveryClient 
public  class RibbonServiceApplication {
     public  static  void main (String [] args) { 
        SpringApplication.run (RibbonServiceApplication. Class , args); 
    } 

    / ** 
     * instantiated RestTemplate, opening balancing load by @LoadBalanced annotation 
     * / 
    @Bean 
    @LoadBalanced 
    public RestTemplate RestTemplate () {
         return  new new RestTemplate (); 
    } 
}

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Call service Service-1 provides:

@Service
public class UserService {

    @Autowired
    private RestTemplate restTemplate;

    public UserDto getUser(Long userId) {
        ResponseEntity<UserDto> responseEntity = restTemplate.getForEntity("http://service-1/getUser/{1}", UserDto.class, userId);
        return responseEntity.getBody();
    }
}

View Code

After the turn starts registry, Service-1 and the Ribbon two instances, all successful start, start service-1 can be seen two examples, as shown below: 

Access Ribbon client interface: http: // localhost: 9000 / user / getByUserId

Refresh the page, the back-end Service-1 are two examples of output log:

service-1:8091

8091 provides service

service-1:8092

8092 provides service
8092 provides service

The system architecture as shown:

 2, Ribbon Configuration

Automated configuration

Load balancing process above does not build any Ribbon-related configuration, the default configuration is done a lot since Spring Cloud integration Eureka and Ribbon time.

In the absence of the introduction of Spring Cloud Eureka, Spring Cloud Ribbon has achieved these default configuration bean:

• IClientConfig: Ribbon client configuration defaults com.netflix.client.config.DefaultClientConfigImpl 

• IRule: Ribbon load balancing strategy, defaults com.netflix.loadbalancer.ZoneAvoidanceRule

• IPing: Ribbon instance heartbeat checking policy, defaults com.netflix.loadbalancer.NoOpPing, it can be seen by looking to achieve: do not check the instance is available, always returns true

• ServerList: Service maintains a list of list of examples, defaults com.netflix.loadbalancer.ConfigurationBasedServerList

• ServerListFilter: Service Instance list filtering mechanisms, defaults org.springframework.cloud.netflix.ribbon.ZonePreferenceServerListFilter

• ILoadBalancer: load balancer, defaults com.netflix.loadbalancer.ZoneAwareLoadBalancer

Custom configuration: Code + RibbonClient manner

@RibbonClient(value = "service-1", configuration = MyRibbonConfig.class)
public class RibbonServiceApplication {

Custom random load when:

@Configuration
public class MyRibbonConfig {
    @Bean
    public IRule ribbonRule() {   new RandomRule();   }
}

When the load is changed to customize the polling:

@Configuration
public class MyRibbonConfig {
    @Bean
    public IRule ribbonRule() {   new RoundRobinRule();   }
}

Respectively, in the above two cases refresh the page http: // localhost: 9000 / user / getByUserId (to refresh eight times, for example, observation log two examples of service-1 console print):

• Found that when RandomRule service-1 is supplied in 8091 and 8092 two service instances.
• It found that when the rotation is RoundRobinRule service-1 in 8091 and 8092 to provide two service instances.

Custom configuration: Code + profile mode ( Components of Load Balancer )

In the properties in the configuration, created by the reflection mode, configuration is as follows:

以 `<clientName>.ribbon.` 为前缀，加上下面的属性名（属性名来自 org.springframework.cloud.netflix.ribbon.PropertiesFactory 类）：

NFLoadBalancerClassName
NFLoadBalancerRuleClassName
NFLoadBalancerPingClassName
NIWSServerListClassName
NIWSServerListFilterClassName

Configuring ribbon load mode (for service-1 service settings):

service-1:
  ribbon:
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

The custom class assigned to the corresponding levels of service attributes can be done custom configuration.

3, Appendix

　　This article Demo Address: Ribbon Service