1. Nacos introduction

Nacos is the acronym for Dynamic Naming and Configuration Service, a dynamic service discovery, configuration management and service management platform that is easier to build cloud-native applications.

2. nacos vs. Eureka

registration center	Spring Cloud Nacos	Spring Cloud Eureka
CAP model	Supports AP and CP models	AP model
Client update service information	Use register+DNS-f+health check mode. The DNS-F client uses push/pull in listening mode to pull update information	The client regularly polls the server to obtain the IP information of other services and compares it. In contrast, the server is under greater pressure and has a greater delay
Scalability	Using the Raft election algorithm has better performance, availability, and fault tolerance, and new nodes do not need to broadcast synchronization information with all nodes	Due to the use of broadcast synchronization information, the eureka cluster is under great pressure after the cluster exceeds 1000 machines
Health check mode/method	Support server/client/close inspection mode, inspection methods include tcp, http, sql. Support for building your own health checker	The client sends an http heartbeat to the server
load balancing	support	support
Manual online and offline service mode	Via console page and API	By calling the API
Synchronization across centers	support	not support
k8s integration	support	not support
group	Nacos can be used for group management according to business and environment	not support
Weights	Nacos provides the weight setting function by default to adjust the bearing traffic pressure	not support
manufacturers	alibaba	Netflix

3. nacos installation

Official installation (too slow to download): Download the installation guide

docker install

#拉取镜像
docker pull nacos/nacos-server 
#创建容器
 docker run -d -p 8848:8848 -e MODE=standalone -e PREFER_HOST_MODE=hostname -v /usr/app/nacos/init.d/custom.properties:/home/nacos/init.d/custom.properties -v /usr/app/nacos/logs:/home/nacos/logs --restart always --name nacos nacos/nacos-server

Enter the background page address localhost::8848/nacos default account/password admin/admin
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4. nacos registration center

We use nacos as the registration center, create two services, A and B, and register them in nacos, and use openfeign+ribbon to implement B service to call A service interface

4.1 Service A is registered in nacos

A service pom dependencies (only add nacos dependencies, add other dependencies according to your needs)

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

A service configuration file bootstrap.yml

Note: When the springboot service starts, it first looks for the bootstrap.yml configuration file, then looks for the application.yml, and finally merges the two contents

server:
  port: 8099
  #服务名称
spring:
  application:
    name: a-server
    #ncaos地址
  cloud:
    nacos:
      discovery:
        server-addr: 127.0.0.1:8848
# 指定开放的端点路径， * 代表全部
management:
  endpoints:
    web:
      exposure:
        include: '*'

3. Create a service startup class, add@EnableDiscoveryClient

During the project startup process, it is found that the startup class needs to be placed in the third-level directory, and an error will be reported

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

4. Create a controller class.
We expose a service interface to the outside, use B service later, obtain the interface address through nacos, and finally call

@RestController
@RequestMapping("/Aserver")
public class AserverController {
    
    

    @GetMapping("/getRandom")
    private String getRandom() {
    
    
        Random random = new Random();
        int i = random.nextInt();
        return "本次刷新值为:" + i;
    }
}
 }
}

4.2 Create B service and put it in nacos

1. Add dependencies

       <!-- openfeign 依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud </groupId>
            <artifactId>spring-cloud-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

2. Create B service configuration file bootstrap.yml configuration

server:
  port: 9093
spring:
  application:
    name: b-server
  cloud:
    nacos:
      discovery:
        server-addr: 39.105.151.241:8848
management:
  endpoints:
    web:
      exposure:
        include: '*'

3. Create B service startup class


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

4. Create an openfeign interface

The @FeignClient annotation is the annotation name in openfeign and is the spring.application.name value in the A service configuration file.

@Component
@FeignClient(name = "a-server")
@RequestMapping("/provider")
public interface AserverService{
    
    
    @GetMapping("/getRandom")
     String providerCase();
}

5. Create the Controller class of B service and call the interface of A service

@RestController
public class AServerController {
    
    
    @Autowired
    private AserverService AserverService;

    @GetMapping("getId")
    public String getId() {
    
    
        String s = AserverService.getRandom();
        return "A服务返回结果"+s;
    }

}

6. We start A and B projects and enter the nacos page to view the service list

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7. Call http://localhost:9093/getId

5 Configuration Center

The dynamic configuration service allows you to centralize, externalize and dynamically manage the application configuration and service configuration of all environments. Dynamic configuration eliminates the need to redeploy applications and services when configuration changes, making configuration management more efficient and agile

Introduce dependency in A service

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
        </dependency>

A service bootsrap.yml configuration file content

server:
  port: 8099
spring:
  application:
    name: a-server
    #ncaos地址
  cloud:
    nacos:
      discovery:
        server-addr: 39.105.151.241:8848
      #配置中心的地址
      config:
        server-addr: 39.105.151.241:8848
        file-extension: yml
# 指定开放的端点路径， * 代表全部
management:
  endpoints:
    web:
      exposure:
        include: '*'
#我们需要更新配置内容
config:
  info: a_server_test_01

Create a test interface

The @RefreshScope annotation will automatically update the configuration file

@RestController
@RequestMapping("/config")
@RefreshScope
public class ConfigInfoController {
    
    

    @Value("${config.info}")
    private  String configInfo;

    @GetMapping("/getInfo")
    public  String getConfigInfo(){
    
    
        return  "配置内容:"+configInfo;
    }