Simple load balancing with Nacos

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One 、 What is? Nacos？

English full name ：Dynamic Naming and Configuration Service
It is a dynamic service discovery developed by Alibaba team that is easier to help build cloud native applications 、 Configuration and service management platform
Nacos Provides a range of easy-to-use features , It can help us realize dynamic service discovery quickly 、 Service configuration and other functions .

Two 、Nacos Download and install

—> Reference documents
—> github download
—> Image download

The official recommendation is to download 2.0.3 Stable version

1. Use Windows start-up

cmd Input

startup.cmd -m standalone

2. verification nacos Start successfully or not

http://192.168.10.236:8848/nacos/index.html
account number ：nacos , password ：nacos

3、 ... and 、Nacos Discovery Service registration / Find out

1. First, introduce dependency ：

        <!-- https://mvnrepository.com/artifact/com.alibaba.cloud/spring-cloud-starter-alibaba-nacos-discovery -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            <version>2021.1</version>
        </dependency>

2. To configure nacos The address of ：

nacos.discovery.server-addr=127.0.0.1:8848

3. Add... To the startup class @EnableDiscoveryClient annotation

4. see Nacos Service list status

This proves that our port is registered as a service Nacos In the ！

5. The service list does not show problems

In ensuring that Nacos Normal start , The above operations are also configured , When the service name and other information are not displayed , Please check spring-boot-starter-parent Version of ：

Four 、 Easy load balancing

You need to create two registrants （9001、9002） And a consumer （8083）

1. Registrant configuration

server:
  port: 9001
Spring:
  application:
    name: nacos-provider
  cloud:
    discovery:
      server-addr: localhost:8848
management:
  endpoint:
    web:
      exposure:
        include: '*'

2. Registrant startup class

@EnableDiscoveryClient // Turn on the registration and discovery function of the service 
@SpringBootApplication
public class Port9001Application {
    
    public static void main(String[] args) {
    
        SpringApplication.run(Port9001Application.class, args);
    }
}

3. Registrant business layer

@RestController
public class Port9001 {
    
    @Value("${server.port}")
    private String serverPort;
    @GetMapping("/getPort")
    public String getServerPort(){
    
        return " Call port  " + serverPort + "  success ！";
    }
}

4. Consumer configuration

server:
  port: 8083
Spring:
  application:
    name: nacos-consumer
  cloud:
    discovery:
      server-addr: localhost:8848
# The name of the micro service the consumer is going to visit 
service-url:
  nacos-user-service: http://nacos-provider

5. Consumer startup class

@EnableDiscoveryClient
@SpringBootApplication
public class NacosConsumer8083Application {
    
    public static void main(String[] args) {
    
        SpringApplication.run(NacosConsumer8083Application.class, args);
    }
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
    
        return new RestTemplate();
    }
}

6. Consumer business

@RestController
public class Port8083Controller {
    
    @Autowired
    private RestTemplate restTemplate;
    @Value("${service-url.nacos-user-service}")
    private String serverURL;
    @GetMapping(value = "consumer/nacos")
    public String getDiscovery(){
    
        /*  Three parameters ： Fill in the name of the visit and url Address  +  The return value type of the calling interface  */
        return restTemplate.getForObject(serverURL+"/getPort",String.class);
    }
}

7. Start calling the interface

call 8083 Of /consumer/nacos
Refresh the page again

This proves that the remote call is completed , At the same time, it has the effect of load balancing ！

8. Solve the problem

java.net.UnknownHostException: nacos-provider

Add... To the dependency spring-cloud-loadbalancer that will do ！