Eureka服务注册与发现

服务治理

Spring Cloud封装了Netflix公司开发的Eureka模块来实现服务治理。

在传统的rpc远程调用框架中，管理每个服务与服务之间依赖关系比较复杂，管理比较复杂，所以需要使用服务治理，管理服务于服务之间的依赖关系，可以实现服务调用、负载均衡、容错等，实现服务发现与注册。

服务注册与发现

Eureka采用了CS的设计架构，Eureka Server作为服务注册功能的服务器，它是服务注册的中心。而系统中其他的微服务，使用了Eureka的客户端连接到Eureka Server并维持心跳连接。这样系统的维护人员就可以通过Eureka Server来监控系统中各个微服务是否正常运行。

在服务注册与发现中，有一个注册中心。当服务器启动的时候，会把当前自己服务器的信息比如服务地址通讯地址等以别名方式注册到注册中心上。另一方(消费者|服务提供者)，以该别名的方式去注册中心上获取到实际的服务通讯地址，然后再实现本地RPC调用RPC远程调用框架核心设计思想：在于注册中心上，因为使用注册中心管理每个服务与服务之间的一个依赖关系(服务治理概念).在任何rpc远程框架中,都会有一个注册中心(存放服务地址相关信息(接口地址));

左边是Eureka系统架构,右边是Dubbo的架构

1596525780055

Eureka包含两个组件:Eureka Server和Eureka Client

Eureka Server提供服务注册服务
各个微服务节点通过配置启动,会在EurekaServer中进行注册,这样EurekaServer中的服务注册表中将会存储所有可用服务节点的信息,服务节点的信息可以在界面中直观看到.
EurekaClient通过注册中心进行访问
是一个Java客户端,用于简化Eureka Server的交互,客户端同时也具备一个内置的、使用轮询(round-robin)负载算法的负载均衡器.在应用启动后,将会向Eureka Server发送心跳(默认周期为30秒)。如果Eureka Server在多个心跳周期内没有接受到某个节点的心跳，EurekaServer将会从服务注册表中把这个服务节点移除(默认90秒)。

1596526701490

服务端安装

新建model:cloud-eureka-server7001

pom.xml

 <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency><!--引入自己定义的api通用包，可以使用Payment支付Entity-->
            <groupId>com.kayleh.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <!--boot web actuator-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
    </dependencies>

applicaiton.yml

server:
  port: 7001
eureka:
  instance:
    hostname: localhost  # 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/

主启动类

package com.kayleh.springcloud;

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

/**
 * @Author: Wizard
 * @Date: 2020/8/4 15:57
 */
@SpringBootApplication
@EnableEurekaServer
public class EurekaMain7001 {
    public static void main(String[] args) {
        SpringApplication.run(EurekaMain7001.class, args);
    }
}

访问 http://localhost:7001

支付微服务8001入驻进EurekaServer

微服务8001的pom文件:添加坐标

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

application.yml下添加

eureka:
  client:
    # 表示是否将自己注册进eurekaServer默认为true
    register-with-eureka: true
    # 表示从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
    fetch-registry: true
    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://localhost:7001/eureka

主启动类添加client注解

@SpringBootApplication
@EnableEurekaClient
public class PaymentMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8001.class, args);
    }
}

微服务注册名配置说明

1596529308640

访问Eureka出现红字原因:

自我保护机制.

配置微服务80进驻Eureka;

改pom,添加坐标

改yml

server:
  port: 80

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
    # 表示从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
    fetch-registry: true
    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://localhost:7001/eureka

主启动类添加client注解.

集群eureka构建

eureka集群原理分析

1596544509634

解决办法:搭建eureka注册中心集群,实现负载均衡+故障容错

构建集群(单机走向集群)

新建model:cloud-eureka-server7002

复制微服务7001的pom.xml

修改C:\Windows\System32\drivers\etc目录下的hosts文件

添加进hosts文件

127.0.0.1 eureka7001.com
127.0.0.1 eureka7002.com

修改7001和7002的application.yml (如果是三台集群的话,在service-url下继续写,用逗号分隔开)

7001:
server:
  port: 7001
  
eureka:
  instance:
    hostname: eureka7001.com #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:
      defaultZone: http://eureka7002.com:7002/eureka/
--------------------------------------------------------
7002:
server:
  port: 7002
  
eureka:
  instance:
    hostname: eureka7002.com #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:
      defaultZone: http://eureka7001.com:7001/eureka/

7002启动类加注解

访问

eureka7001.com:7001
eureka7002.com:7002

将80和8001模块注册进eureka, 修改yaml文件

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

测试

http://localhost/consumer/payment/get/1

支付服务提供者8001集群环境构建

新建cloud-provider-payment8002

pom.xml和8001一致

copy 8001的yml文件到8002,修改端口号

server:
	port: 8002

主启动类,业务类直接cpoy8001

修改8001和8002的controller

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

修改打印
"插入数据库成功,serverPort" + serverPort
"查询成功,serverPort:" + serverPort

负载均衡

修改消费者80模块的OrderController的订单服务访问地址

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

1596602970422

修改ApplicationContextConfig

@Configuration
public class ApplicationContextConfig {
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
}
添加@LoadBalanced开启RestTemplate的负载均衡

测试

http://localhost/consumer/payment/get/1

可以看到8001端口和8002端口交替出现.

Ribbon和Eureka整合后,Consumer可以直接调用服务而不用关心地址和端口号,且该服务还有负载功能.

axtuator微服务信息完善

当前问题

1596603735423

暴露主机名

修改cloud-provider-payment8001和8002 的yml

eureka:
  client:
    # 表示是否将自己注册进eurekaServer默认为true
    register-with-eureka: true
    # 表示从eurekaServer抓取已有的注册信息，默认为true。单节点无所
    fetch-registry: true
    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://localhost:7001/eureka/
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/
  instance:
    instance-id: payment8001
添加instance配置

更改之后

1596604101892

点开链接,测试

http://wizard:8002/actuator/health

访问地址显示ip地址

修改8001,8002的yml,添加

instance:
   instance-id: payment8001
   prefer-ip-address: true

服务发现Discovery

对于注册进eureka里面的微服务,可以通过服务发现来获得该服务的信息.

修改8001的controller

添加
@Resource
private DiscoveryClient discoveryClient;

@GetMapping(value = "/payment/discovery")
public Object discovery() {
      List<String> services = discoveryClient.getServices();
      for (String element : services) {
            log.info("----------element:" + element);
      }
      List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");
      for (ServiceInstance instance : instances) {
         log.info(instance.getServiceId() + "\t" + instance.getHost() + "\t" + 			     	  instance.getPort() + "\t" + instance.getUri());
      }
        return this.discoveryClient;
    }

启动类添加注解

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
public class PaymentMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8001.class, args);
    }
}

测试

http://localhost:8001/payment/discovery
------------------------------------------
{"services":["cloud-order-service","cloud-payment-service"],"order":0}

1596605686156

Eureka的自我保护机制

故障现象:

1596605819802

导致原因:

某时刻某一个微服务不可用了,Eureka不会立刻清理,依旧会对该微服务的信息进行保存.
属于CAP里面的AP分支

1596606071261

1596606189669

1596606288542

关闭自我保护

修改7001的yaml

添加 
server:
	enable-self-preservation: false
---------------------------------------
eureka:
  instance:
    hostname: eureka7001.com
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://eureka7002.com:7002/eureka/
  server:
    #关闭自我保护机制，保证不可用服务被及时删除
    enable-self-preservation: false
    #时间间隔
    eviction-interval-timer-in-ms: 2000

8001的yml加入

  instance:
    instance-id: payment8001
    prefer-ip-address: true
    # 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）
    lease-expiration-duration-in-seconds: 1
    # 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），超时将剔除服务
    lease-renewal-interval-in-seconds: 2

Zookepper

需要Linux安装Zookepper

新建工程cloud-provider-payment8004

pom.xml

<dependencies>
        <!--        Zookeeper客户端-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
        </dependency>

        <dependency><!--引入自己定义的api通用包，可以使用Payment支付Entity-->
            <groupId>com.kayleh.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--        热部署-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
    </dependencies>

application.yml

server:
  port: 8004

#服务别名
spring:
  application:
    name: cloud-provider-payment
  cloud:
    zookeeper:
      # zookeeper的机器ip加端口号
      connect-string: 192.168.111.144:2181

启动类

package com.kayleh.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

/**
 * @Author: Wizard
 * @Date: 2020/8/5 16:58
 */
@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain8004 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8004.class, args);
    }
}

PaymentController

package com.kayleh.springcloud.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.UUID;

/**
 * @Author: Wizard
 * @Date: 2020/8/5 17:00
 */
@RestController
@Slf4j
public class PaymentController {
    @Value("${server.port}")
    private String serverPort;

    @RequestMapping(value = "/payment/zk")
    public String paymentzk() {
        return "Springcloud with zookeeper:" + serverPort + "\t" + UUID.randomUUID().toString();
    }
}

jar包冲突

 <!--        Zookeeper客户端-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zookeeper-discovery</artifactId>
            <!--            排除自带的zookeeper3.5.3-->
            <exclusions>
                <exclusion>
                    <groupId>org.apache.zookeeper</groupId>
                    <artifactId>zookeeper</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--        添加zookeeper3.4.9-->
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.4.9</version>
        </dependency>

测试

1596618784943

访问

localhost:8004/payment/zk

1596618927219

是临时节点，项目停止后，连接会持续一小段时间，然后丢失。重新连接后是另一个UUID的Zookepper。

1596626952182

订单服务注册zookeeper

新建cloud-consumerzk-order80

复制80的pom

yml

server:
  port: 80

#服务别名
spring:
  application:
    name: cloud-consumer-order
  cloud:
    zookeeper:
      # zookeeper的机器ip加端口号
      connect-string: 192.168.111.144:2181

启动:

package com.kayleh.springcloud;

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

config:

package com.kayleh.springcloud.config;

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

controller

package com.kayleh.springcloud.controller;

@RestController
@Slf4j
public class OrderZkController {
    public static final String INVOKE_URL = "http://cloud-provider-payment";
    @Resource
    private RestTemplate restTemplate;

    @GetMapping("/consumer/payment/create")
    public CommonResult<Payment> create(Payment payment) {
        return restTemplate.postForObject(INVOKE_URL + "/payment/create", payment, CommonResult.class);
    }

    @GetMapping("/consumer/payment/get/{id}")
    public CommonResult<Payment> getPayment(@PathVariable("id") Long id) {
        return restTemplate.getForObject(INVOKE_URL + "/payment/get/" + id, CommonResult.class);
    }
}

服务访问地址INVOKE_URL填linux上的zookeeper名称

1596627798682

测试,启动 80zk 和 8004.

1596628332087

访问

http://localhost/consumer/payment/zk

Consul

1596629165834

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

1596629552902

启动

consul agent -dev

访问

http://localhost:8500/ui/

服务提供者注册进Consul

新建模块cloud-providerConsul-payment8006

pom.xml

    <dependencies>
        <!--consul-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-consul-discovery</artifactId>
        </dependency>

        <dependency><!--引入自己定义的api通用包，可以使用Payment支付Entity-->
            <groupId>com.kayleh.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <!--        mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <!--        热部署-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
    </dependencies>

yml

server:
  port: 8006

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

主启动类

controller

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

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

测试

http://localhost:8006/payment/consul

服务消费者注册进Consul

新建模块cloud-consumer-consul-order80

pom.xml

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-consul-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

主启动类

复制cloud-consumerzk-order80模块的ApplicationContextConfig

controller

@RestController
@Slf4j
public class OrderConsulController {
    public static final String INVOKE_URL = "http://consul-provider-payment";
    @Resource
    private RestTemplate restTemplate;

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

}