SpringCloud 【二】 --- 服务注册中心 (Eureka、Zookeeper、Consul)

---

一、Eureka服务注册与发现 (×)

单机Eureka构建步骤

(1) EurekaServer 服务端搭建

① 新建模块 cloud-eureka-server7001

② 配置 pom.xml

<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>cloud2020artifactId>
        <groupId>com.atguigu.springcloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-eureka-server7001artifactId>

    <dependencies>
        
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-eureka-serverartifactId>
        dependency>
        
        <dependency>
            <groupId>com.lun.springcloudgroupId>
            <artifactId>cloud-api-commonsartifactId>
            <version>${project.version}version>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
            <scope>runtimescope>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
        dependency>
    dependencies>
project>

③ 配置 application.yml

server:
  port: 7001

eureka:
  instance:
    hostname: locathost #eureka服务端的实例名称
  client:
    #false表示不向注册中心注册自己。
    register-with-eureka: false
    #false表示自己端就是注册中心，我的职责就是维护服务实例，并不需要去检索服务
    fetch-registry: false
    service-url:
      #设置与Eureka server交互的地址查询服务和注册服务都需要依赖这个地址。
      defaultZone: http://${
     eureka.instance.hostname}:${
     server.port}/eureka/

④ 主启动类

@SpringBootApplication
@EnableEurekaServer // 表示为EurekaServer
public class EurekaMain7001 {
     
    public static void main(String[] args) {
     
        SpringApplication.run(EurekaMain7001.class, args);
    }
}

⑤ 测试

eureka服务有了，但是没有客户(有server但是client没有注册进去)

(2) 将支付微服务8001注册到 EurekaServer

① 添加依赖到pom.xml

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

② 添加配置到 application.yml

eureka:
  client:
    #表示是否将自己注册进Eurekaserver默认为true。
    register-with-eureka: true
    #是否从EurekaServer抓取已有的注册信息，默认为true。单节点无所谓，集群必须设置为true才能配合ribbon使用负载均衡
    fetchRegistry: true
    service-url:
      defaultZone: http://localhost:7001/eureka

③ 主启动类上加注解 @EnableEurekaClient

@EnableEurekaClient // 表明是EurekaClient

④ 测试

(3) 将订单微服务80注册到 EurekaServer

① 添加依赖到 pom.xml

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

② 添加配置到 application.yml

spring:
  application:
    name: cloud-order-service

eureka:
  client:
    #表示是否将自己注册进Eurekaserver默认为true。
    register-with-eureka: true
    #是否从EurekaServer抓取已有的注册信息，默认为true。单节点无所谓，集群必须设置为true才能配合ribbon使用负载均衡
    fetchRegistry: true
    service-url:
      defaultZone: http://localhost:7001/eureka

③ 主启动类上加注解 @EnableEurekaClient

@EnableEurekaClient // 表明是EurekaClient

④ 测试

---

集群Eureka构建步骤

Eureka 集群

解决办法: 搭建Eureka注册中心集群,实现负载均衡+故障容错

(1) Eureka集群环境构建步骤

① 新建模块 cloud-eureka-server7002

pom中依赖和7001相同

② 修改映射配置

找到C:\Windows\System32\drivers\etc路径下的hosts文件

127.0.0.1 eureka7001.com
127.0.0.1 eureka7002.com

通过命令：ipconfig /flushdns 刷新hosts文件

③ 7001的 application.yml

server:
  port: 7001
spring:
  application:
    name: cloud-eureka-service
eureka:
  instance:
    # eureka服务端的实例名称
    hostname: eureka7001.com
  client:
    # false表示不向注册中心注册自己
    register-with-eureka: false
    # false表示自己端就是注册中心,我的职责就是维护服务实例,并不需要检索服务
    fetch-registry: false
    service-url:
      # 设置与Eureka Server交互的地址查询服务和注册服务都需要依赖这个地址
      defaultZone: http://eureka7002.com:7002/eureka/

④ 7002的 application.yml

server:
  port: 7002
spring:
  application:
    name: cloud-eureka-service2
eureka:
  instance:
    hostname:  eureka7002.com
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/

⑤ 7002的主启动类

@SpringBootApplication
@EnableEurekaServer
public class EurekaMain7002 {
     
    public static void main(String[] args) {
     
        SpringApplication.run(EurekaMain7002.class, args);
    }
}

⑥ 测试

(2) 将支付服务8001，和订单服务80微服务发布到上面2台Eureka集群配置中

① 修改二者 yaml 即可

defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka # 集群版

② 测试

(3) 支付服务提供者8001集群环境搭建

① 新建模块 cloud-provider-payment8002

pom文件的依赖和8001相同
yaml文件除了server-port为8002，其他与8001的都相同
主启动类
业务类也与8001相同

② 修改8001和8002的controller

取出yaml中的servre-port，便于测试时的分析

@Value("${server.port}")
private String serverPort;

③ 修改80客户端的 PAYMENT_URL

订单服务的访问地址不能写si，之前是指定的8001，现在支付服务是集群环境，所以需要用服务名进行访问

public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE";

由于一个集群中有多个服务，所以此时使用客户80访问时，会报错，因为不知道具体访问的是集群中的哪个服务，所以需要在 getRestTemplate上添加一个注解@LoadBalanced均衡负载，循环访问集群中的每个服务

④ 测试

---

actuator微服务信息完善

(1) 主机名称:服务名称修改

修改yaml文件

eureka:
	instance:
     	instance-id: payment8001 #修改服务名称

(2) 访问信息有IP信息提示

此时没有IP信息显示

修改yaml文件

prefer-ip-address: true # 访问路径可以显示ip信息

---

服务发现Discovery

对于注册eureka里面的微服务,可以通过服务发现来获得该服务的信息

(1) 修改cloud-provider-payment8001的Controller

注意discoveryClient的包时spring的那个，如果没有.getServices()，可以看看是不是包导错了

// 服务发现 获取服务信息
@Resource
private DiscoveryClient discoveryClient;

@GetMapping("/payment/discover")
public DiscoveryClient discover() {
     

    // 获取注册中心的服务列表
    List<String> services = discoveryClient.getServices();

    for (String service : services) {
     
        log.info("****服务：" + service);
    }

    // 获取某个服务的实例
    List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");

    for (ServiceInstance instance : instances) {
     
        log.info("服务cloud-payment-service中有： " + "\t" + instance.getServiceId() + "\t" + instance.getInstanceId() + "\t" + instance.getHost());
    }

    return this.discoveryClient;
}

(2) 8001的启动类添加@EnableDiscoveryClient

就用原来的@EnableEurekaClient似乎也是可以的

@SpringBootApplication
// 表明是EurekaClient,且只适用于Eureka注册中心
@EnableEurekaClient
// 二者都是可以让注册中心发现,扫描到该服务,区别在于EnableEurekaClient只适用于Eureka注册中心,而EnableDiscoveryClient可以为其他注册中心
@EnableDiscoveryClient
public class PaymentMain8001 {
     
    public static void main(String[] args) {
     
        SpringApplication.run(PaymentMain8001.class, args);
    }
}

(3) 测试

---

eureka自我保护

(1) 故障现象

(2) 导致原因

(3) 如何禁止自我保护

① 7001的yaml中关闭自我保护模式

enable-self-preservation: false # 禁止eureka的自我保护,服务一旦没有"心跳",就会被剔除

② 8001中修改配置，方便测试查看效果

lease-renewal-interval-in-seconds: 1 # Eureka客户端向服务端发送心跳的时间间隔,单位为秒(默认是30秒)e

lease-expiration-duration-in-seconds: 2 # Eureka服务端在收到最后一次心跳后等待时间上限 ,单位为秒(默认是90秒),超时剔除服务

③ 测试

可以同时启动 7001(禁用自我保护) 和 7002(默认开启自动保护)，然后启动8001，再stop 8001，就可以看到 7001中很快剔除8001，而7002中还有

---

二、Zookeeper服务注册与发现 (√)

注册中心Zookeeper

Zookeeper是一个分布式协调工具,可以实现注册中心功能

Zookeeper服务器 取代 Eureka服务器,zk作为服务注册中心

---

服务提供者

(1) 新建模块 cloud-provider-payment8004

(2) 配置 pom.xml

<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>cloud2020artifactId>
        <groupId>com.atguigu.springcloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-provider-payment8004artifactId>

    <dependencies>
        <dependency>
            <groupId>com.atguigu.springcloudgroupId>
            <artifactId>cloud-api-commonartifactId>
            <version>${project.version}version>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-zookeeper-discoveryartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
            <scope>runtimescope>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

project>

(3) 配置 application.yml

server:
  port: 8004 # 8004表示注册到zookeeper服务器的支付服务提供者端口号

spring:
  application:
    name:  cloud-provider-payment # 服务别名---注册zookeeper到注册中心的名称
  cloud:
    zookeeper:
      connect-string: 192.168.44.129:2181 # 默认localhost:2181

(4) 创建主启动类

@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain8004 {
     
    public static void main(String[] args) {
     
        SpringApplication.run(PaymentMain8004.class, args);
    }
}

(5) 启动8004注册进zookeeper

【 PS: 由于zookeeper的半数机制，最少必须启动三个server，一开始只启动了一个，然后启动了一会儿就一直报错。】

① 启动 zookeeper

bin/zkServer.sh start

② 启动后问题

jar 包冲突

③ 问题出现的原因

调整 pom.xml

<dependency>
    <groupId>org.springframework.cloudgroupId>
    <artifactId>spring-cloud-starter-zookeeper-discoveryartifactId>
    <exclusions>
        
        <exclusion>
            <groupId>org.apache.zookeepergroupId>
            <artifactId>zookeeperartifactId>
        exclusion>
    exclusions>
dependency>

<dependency>
    <groupId>org.apache.zookeepergroupId>
    <artifactId>zookeeperartifactId>
    <version>3.4.10version>
dependency>

④ 测试

此时关闭8004后，zookeeper中的节点不在了，由此可见，创建的服务节点是临时节点。

---

服务消费者

(1) 新建模块 cloud-consumerzk-order80

(2) 配置 pom.xml

<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>cloud2020artifactId>
        <groupId>com.atguigu.springcloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-consumerzk-order80artifactId>

    <dependencies>
        <dependency>
            <groupId>com.atguigu.springcloudgroupId>
            <artifactId>cloud-api-commonartifactId>
            <version>${project.version}version>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-zookeeper-discoveryartifactId>
            <exclusions>
                
                <exclusion>
                    <groupId>org.apache.zookeepergroupId>
                    <artifactId>zookeeperartifactId>
                exclusion>
            exclusions>
        dependency>
        
        <dependency>
            <groupId>org.apache.zookeepergroupId>
            <artifactId>zookeeperartifactId>
            <version>3.4.10version>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
            <scope>runtimescope>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

project>

(3) 配置 application.yml

server:
  port: 80

spring:
  application:
    name: cloud-consumer-order # 服务别名
  cloud:
    zookeeper:
      connect-string: 192.168.44.129:2181 # 注册到zookeeper地址

(4) 创建主启动类

@SpringBootApplication
@EnableDiscoveryClient
public class OrderZkMain80 {
     
    public static void main(String[] args) {
     
        SpringApplication.run(OrderZkMain80.class, args);
    }
}

(5) 业务类

① 配置bean：ApplicationContextConfig

@Configuration
public class ApplicationContextConfig {
     
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate() {
     
        return new RestTemplate();
    }
}

② 创建 OrderZkController

@RestController
@Slf4j
public class OrderZkController {
     
    private String url = "http://cloud-provider-payment";

    @Resource
    private RestTemplate restTemplate;

    @GetMapping("/consumer/payment/zk")
    public String paymentInfo() {
     
        return restTemplate.getForObject(url+"payment/zk", String.class);
    }
}

(6) 测试

---

三、Consul服务注册与发现 (√)

Consul简介

(1) 是什么

https://www.consul.io/intro/index.html

(2) 能干嘛

• 服务发现：提供HTTP/DNS两种发现方式
• 健康检测：支持多种方式,HTTP、TCP、Docker、shell脚本定制化
• KV存储： Key、Value的存储方式
• 多数据中心：Consul支持多数据中心
• 可视化界面

(3) 在哪下 (本机：windows版本)

https://www.consul.io/downloads.html

(4) 怎么玩

https://www.springcloud.cc/spring-cloud-consul.html

---

安装并运行Consul

(1) 官网说明

https://learn.hashicorp.com/consul/getting-started/install.html

(2) 安装

(3) 使用开发模式启动

consul agent -dev

http://localhost:8500/ui/dc1/services

---

服务提供者

(1) 新建模块 cloud-providerconsul-payment8006

(2) 配置 pom.xml

<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>cloud2020artifactId>
        <groupId>com.atguigu.springcloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-providerconsul-payment8006artifactId>

    <dependencies>
        
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-consul-discoveryartifactId>
        dependency>
        <dependency>
            <groupId>com.atguigu.springcloudgroupId>
            <artifactId>cloud-api-commonartifactId>
            <version>${project.version}version>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
            <scope>runtimescope>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>
project>

(3) 配置 application.yml

server:
  port: 8006 # consul服务端口

spring:
  application:
    name: cloud-provider-payment
  cloud:
    consul: # consul注册中心地址
      host: localhost
      port: 8500
      discovery:
        hostname: 127.0.0.1
        service-name: ${
     spring.application.name}

(4) 创建主启动类

@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain8006 {
     
    public static void main(String[] args) {
     
        SpringApplication.run(PaymentMain8006.class, args);
    }
}

(5) 创建 PaymentController

@RestController
@Slf4j
public class PaymentController {
     
    @Value("${server.port}")
    private String serverPort;

    @RequestMapping("/payment/consul")
    public String paymentConsul() {
     
        return "SpringCloud with consul:" + serverPort + "\t" + UUID.randomUUID().toString();
    }
}

(6) 测试

---

服务消费者

(1) 新建模块 cloud-consumerconsul-order80

(2) 配置 pom.xml

<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>cloud2020artifactId>
        <groupId>com.atguigu.springcloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <artifactId>cloud-consumerconsul-order80artifactId>

    <dependencies>
        
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-consul-discoveryartifactId>
        dependency>
        <dependency>
            <groupId>com.atguigu.springcloudgroupId>
            <artifactId>cloud-api-commonartifactId>
            <version>${project.version}version>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
            <scope>runtimescope>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
    dependencies>

project>

(3) 配置 application.yml

server:
  port: 80

spring:
  application:
    name: cloud-consumer-order
  cloud:
    consul:
      host: localhost
      port: 8500
      discovery:
        hostname: 127.0.0.1
        service-name: ${
     spring.application.name}

(4) 创建主启动类

@SpringBootApplication
@Slf4j
public class OrderConsulMain80 {
     
    public static void main(String[] args) {
     
        SpringApplication.run(OrderConsulMain80.class, args);
    }
}

(5) 配置bean：ApplicationContextConfig

@Configuration
public class ApplicationContextConfig {
     

    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate() {
     
        return new RestTemplate();
    }
}

(6) 创建 OrderConsulMain80

@RestController
@Slf4j
public class OrderConsulController {
     
    @Resource
    private RestTemplate restTemplate;

    private String INVOKE_URL  = "http://cloud-provider-payment";

    @GetMapping("/consumer/payment/consul")
    public String paymentInfo() {
     
        return restTemplate.getForObject(INVOKE_URL+"/payment/consul", String.class);
    }
}

(7) 测试

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三个注册中心异同点

分区容错性要保证, 所以要么是CP, 要么是AP

• C: Consistency(强一致性)
• A: Availability(可用性)
• P: Parttition tolerance(分区容错性)
• CAP理论关注粒度是否是数据,而不是整体系统设计的策略

AP：eureka

CP(Zookeeper/Consul)

当网络分区出现后,为了保证一致性,就必须拒绝请求,否则无法保证一致性
结论:违背了可用性A的要求,只满足一致性和分区容错,即CP

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