SpringCloud基于Nacos和Eureka 实现双注册双订阅模式，可用于将注册中心Eureka平滑过渡到Nacos的解决方案

前言

大概在去年的时候发现生产环境使用eureka经常会发现服务假死eureka没有给踢掉的情况，然后就衍生了要不就换个注册中心试试，然后就了解到了nacos，正好他还融合了配置中心，但是后来碍于切换时怕生产环境不稳定，丢数据等问题就一直没有换，但后续的项目的注册中心都换成了nacos，这篇文章我就来模拟一下如何将eureka平滑切换成nacos

父工程构建

这里我在父工程里边又单独创建了一层父工程，我分别在alibaba-cloud 、netflix-cloud 中模拟新旧微服务

父工程pom

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>

    <groupId>top.fategroupId>
    <artifactId>nacoAndEurekaartifactId>
    <packaging>pompackaging>
    <version>1.0.0version>
    <modules>
        <module>netflix-cloudmodule>
        <module>alibaba-cloudmodule>
    modules>
project>

---

模拟旧版微服务

 netflix-cloud pom如下 ，因为这里是模拟旧服务，所以都采用旧版本

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>nacoAndEurekaartifactId>
        <groupId>top.fategroupId>
        <version>1.0.0version>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>netflix-cloudartifactId>
    <packaging>pompackaging>
    <modules>
        <module>eurekamodule>
        <module>eureka-providermodule>
        <module>eureka-consumermodule>
    modules>

    <properties>
        <spring.boot.version>2.1.2.RELEASEspring.boot.version>
        <spring.cloud.version>Greenwich.SR5spring.cloud.version>
    properties>

    <dependencyManagement>
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-dependenciesartifactId>
                <version>${spring.boot.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
            
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>${spring.cloud.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>

project>

搭建eureka

• pom依赖如下

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>netflix-cloudartifactId>
        <groupId>top.fategroupId>
        <version>1.0.0version>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>eurekaartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-serverartifactId>
        dependency>
    dependencies>
project>

• EurekaApplication 启动类

package top.fate.eureka;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer
@SpringBootApplication
public class EurekaApplication {

	public static void main(String[] args) {
		SpringApplication.run(EurekaApplication.class, args);
	}
}

• application.yml

server:
  port: 8761
spring:
  application:
    name: eureka-service
eureka:
  instance:
    # 设置该服务注册中心的hostname
    hostname: 127.0.0.1
  client:
    # 我们创建的是服务注册中心，而不是普通的应用，这个应用会向注册中心注册它自己
    #，设置为false就是禁止自己向自己注册的这个种行为
    register-with-eureka: false
    # 不去检索其他的服务，因为注册中心本身的职责就是维护服务实例
    fetch-registry: false
    # 制定服务注册中心的位置
    service-url.defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

---

eureka-provider

• pom依赖如下

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>netflix-cloudartifactId>
        <groupId>top.fategroupId>
        <version>1.0.0version>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>eureka-providerartifactId>

    <properties>
        <maven.compiler.source>8maven.compiler.source>
        <maven.compiler.target>8maven.compiler.target>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
    dependencies>

project>

• EurekaProviderApplication 启动类

package top.fate.eurekaprovider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 14:23
 */
@SpringBootApplication
@EnableEurekaClient
@RestController
public class EurekaProviderApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaProviderApplication.class, args);
    }

    @GetMapping("/info")
    public String info(){
        return "this is eureka-service";
    }
}

• application.yml

server:
  port: 8081
spring:
  application:
    name: provider
eureka:
  client:
    service-url:
      defaultZone: "http://localhost:8761/eureka"

---

eureka-consumer

• pom依赖如下

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>netflix-cloudartifactId>
        <groupId>top.fategroupId>
        <version>1.0.0version>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>eureka-consumerartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
        <dependency>
            <groupId>io.github.openfeigngroupId>
            <artifactId>feign-httpclientartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-openfeignartifactId>
        dependency>
    dependencies>
project>

• EurekaConsumerApplication 启动类

package top.fate.eurekaconsumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
import top.fate.eurekaconsumer.client.EurekaProviderClient;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 14:43
 */
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients(clients = EurekaProviderClient.class)
public class EurekaConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaConsumerApplication.class, args);
    }
}

• EurekaProviderClient

package top.fate.eurekaconsumer.client;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 14:48
 */
@FeignClient(value = "provider")
public interface EurekaProviderClient {

    @GetMapping("info")
    String info();
}

• ConsumerController

package top.fate.eurekaconsumer.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import top.fate.eurekaconsumer.client.EurekaProviderClient;

import javax.annotation.Resource;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 14:48
 */
@RestController
public class ConsumerController {

    @Resource
    private EurekaProviderClient eurekaProviderClient;

    @GetMapping("getProvider")
    public String getProvider(){
        return eurekaProviderClient.info();
    }

}

---

测试服务是否可以调通

这里我三个服务都启动正常，直接访问8091consumer测试 ，如下图所示consumer 可以访问provider

第一阶段流程图

---

模拟新版微服务

alibaba-cloud pom如下，采用最新版技术栈

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>nacoAndEurekaartifactId>
        <groupId>top.fategroupId>
        <version>1.0.0version>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>alibaba-cloudartifactId>
    <packaging>pompackaging>
    <modules>
        <module>nacos-consumermodule>
        <module>nacos-providermodule>
    modules>

    <properties>
        <spring.boot.version>2.6.3spring.boot.version>
        <spring.cloud.version>2021.0.1spring.cloud.version>
        <spring.cloud.alibaba.version>2021.0.1.0spring.cloud.alibaba.version>
    properties>

    <dependencyManagement>
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-dependenciesartifactId>
                <version>${spring.boot.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
            
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>${spring.cloud.version}version>
                <type>pomtype>
                <scope>importscope>
            dependency>
            
            <dependency>
                <groupId>com.alibaba.cloudgroupId>
                <artifactId>spring-cloud-alibaba-dependenciesartifactId>
                <version>${spring.cloud.alibaba.version}version>
            dependency>
        dependencies>
    dependencyManagement>
project>

启动安装nacos

可以参考SpringCloudAlibaba篇（二）整合Nacos注册配置中心 这篇文章我就不重复操作了

---

nacos-provider

• pom 依赖

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>alibaba-cloudartifactId>
        <groupId>top.fategroupId>
        <version>1.0.0version>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>nacos-providerartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>com.alibaba.cloudgroupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discoveryartifactId>
            <version>2021.0.1.0version>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
    dependencies>
project>

• NacosProviderApplication 启动类

package top.fate.nacosprovider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationProperties;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 16:55
 */
@SpringBootApplication
@RestController
@EnableConfigurationProperties(AutoServiceRegistrationProperties.class)
public class NacosProviderApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosProviderApplication.class, args);
    }

    @GetMapping("/info")
    public String info() {
        return "this is nacos-service";
    }
}

• application.properties

spring.autoconfigure.exclude=org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration

• application.yml

url:
  nacos: localhost:8848
server:
  port: 8082
spring:
  application:
    name: provider
  profiles:
    active: dev
  cloud:
    nacos:
      discovery:
        #集群环境隔离
        cluster-name: shanghai
        #命名空间
        namespace: ${spring.profiles.active}
        #持久化实例 ture为临时实例 false为持久化实例  临时实例发生异常直接剔除, 而持久化实例等待恢复
        ephemeral: true
        #注册中心地址
        server-addr: ${url.nacos}
eureka:
  client:
    service-url:
      defaultZone: "http://localhost:8761/eureka"

---

nacos-consumer

• pom依赖

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>alibaba-cloudartifactId>
        <groupId>top.fategroupId>
        <version>1.0.0version>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>nacos-consumerartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>com.alibaba.cloudgroupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discoveryartifactId>
            <version>2021.0.1.0version>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
        dependency>
        <dependency>
            <groupId>io.github.openfeigngroupId>
            <artifactId>feign-httpclientartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-openfeignartifactId>
        dependency>
    dependencies>
project>

• NacosConsumerApplication 启动类

package top.fate.nacosconsumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationProperties;
import org.springframework.cloud.openfeign.EnableFeignClients;
import top.fate.nacosconsumer.client.EurekaProviderClient;
import top.fate.nacosconsumer.client.NacosProviderClient;
import top.fate.nacosconsumer.client.ProviderClient;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 16:39
 */
@SpringBootApplication
@EnableFeignClients(clients = {EurekaProviderClient.class, NacosProviderClient.class, ProviderClient.class})
@EnableConfigurationProperties(AutoServiceRegistrationProperties.class)
public class NacosConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosConsumerApplication.class, args);
    }
}

• ProviderClient

package top.fate.nacosconsumer.client;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 18:24
 */
@FeignClient(value = "provider")
public interface ProviderClient {

    @GetMapping("info")
    String info();
}

• ConsumerController

package top.fate.nacosconsumer.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import top.fate.nacosconsumer.client.ProviderClient;

import javax.annotation.Resource;

/**
 * @auther:Wangxl
 * @Emile:[email protected]
 * @Time:2022/6/16 14:48
 */
@RestController
public class ConsumerController {

    @Resource
    private ProviderClient providerClient;

    @GetMapping("getProvider")
    public String getProvider(){
        return providerClient.info();
    }
}

• application.properties

spring.autoconfigure.exclude=org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration

• application.yml

url:
  nacos: localhost:8848
server:
  port: 8092
spring:
  application:
    name: nacos-consumer
  profiles:
    active: dev
  cloud:
    nacos:
      discovery:
        #集群环境隔离
        cluster-name: shanghai
        #命名空间
        namespace: ${spring.profiles.active}
        #持久化实例 ture为临时实例 false为持久化实例  临时实例发生异常直接剔除, 而持久化实例等待恢复
        ephemeral: true
        #注册中心地址
        server-addr: ${url.nacos}
eureka:
  client:
    service-url:
      defaultZone: "http://localhost:8761/eureka"

上线双注册双订阅新provider服务

先启动nacosProviderApplication

如下图所示，我们已经实现了双注册，nacos和eureka中都注册了服务

nacos

eureka

---

平滑切换注册中心

验证旧consumer

这里我访问8091的旧版Netflix客户端也就是eureka-consumer，看一下调用的是8081 eureka 还是8082 nacos , 这里我反复调用了十几次，返回结果为

• this is nacos-service
• this is eureka-service
  因为此时我们的8091客户端只有eurekaClient，然后我们的provider在eureka注册中心有两个实例，所以就触发了负载均衡，这里我们用的默认轮询模式，当前流程如下图

下线旧provider

现在我们就可以陆续开始平滑切换注册中心了，旧provider可以关掉了，关掉旧provider之后此时的流程就如下图所示了

此时我们再访问旧consumer只会返回 this is nacos-service，因为旧的provider已经下线了 ，新provider当前已经切换完成！

上线双注册双订阅新consumer服务，下线旧consumer

启动nacoConsumerApplication

访问8092验证是否能正常访问，继续访问getProvider接口，如下图所示访问正常，然后我们就可以下线旧consumer服务了

疑惑 （该步骤可以直接略过）

现在我们有个疑惑，现在有两个注册中心，服务发现是走的eureka还是nacos呢
为此，我做了个实验，我分别启动了 旧provider、新provider、新consumer
此时双注册中心的服务

• eureka
• • provider8081、provider8082
• • consumer8092
• nacos
• • provider8082
• • consumer8092

现在我通过consumer8092客户端去请求，得到的结果只有 this is nacos-service ，因此判断注册中心默认走的是nacos.
因为走nacos只会返回this is nacos-service， nacos只有一个实例。
如果走eureka的话会轮询返回this is nacos-service、this is eureka-service ，eureka有两个实例。

• 此时的流程图 虚线代表该线路空闲
  

这里我找了下源码CompositeDiscoveryClient，调用的时候打了断点，发现系统创建了三个discoveryClient ，nacos排在第一个，如果可用的话直接就返回了 ，所以可以理解为默认走的是nacos
这里我想到了nacos有个服务下线功能，如果我将nacos中的服务下线之后应该就会去走eureka了吧

等待几秒过后，通过consumer8092客户端去请求，得到了我想要的结果
分别轮询返回了 this is nacos-service、this is eureka-service，证明已经走eureka了

• 此时流程图虚线代表该线路空闲

最后

此时我们生产上边是 新consumer、新provider、eureka、nacos，既然我们要切换到nacos,那eureka就也要停掉了，我们可以在下一版的服务中去掉 eureka的依赖和配置，只留下nacos，将这一个新版本部署上去之后就可以停掉eureka了

• 如下图所示
  

注意

如果直接引入eureka-client和nacos-client 会报错，如下

Field autoServiceRegistration in org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration required a single bean, but 2 were found:
	- nacosAutoServiceRegistration: defined by method 'nacosAutoServiceRegistration' in class path resource [com/alibaba/cloud/nacos/registry/NacosServiceRegistryAutoConfiguration.class]
	- eurekaAutoServiceRegistration: defined by method 'eurekaAutoServiceRegistration' in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration.class]

1. 需要在配置文件添加如下内容

spring.autoconfigure.exclude=org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationAutoConfiguration

2. 启动类添加注解

@EnableConfigurationProperties(AutoServiceRegistrationProperties.class)

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