Eureka

单例Eureka

首先创建一个 Maven 项目，在 pom.xml 中配置 Eureka 的依赖信息，代码如下所示。

<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>4.0.0</modelVersion>
	<parent>
		<groupId>com.shareprog</groupId>
		<artifactId>shareprog-pom</artifactId>
		<version>1.0.0</version>
	</parent>
	<artifactId>shareprog-eureka</artifactId>
	<name>eureka</name>
	<description>服务发现和治理</description>
	
	<dependencies>
		<!-- eureka-server的依赖 -->
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
		</dependency>
		<!--健康监控-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>
		<!--spring-security-->
		<dependency> 
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-security</artifactId>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<executions>
					<execution>
						<goals>
							<goal>repackage</goal>
						</goals>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>
</project>

接下来在src/main/resource下面创建一个application.yml文件。

server:
  port: 8001
spring:
  application:
    name: eureka
  security:
    user:
      name: eureka
      password: eureka
eureka:
  instance:
    hostname: 127.0.0.1 #UAT应用实例主机名
  client:
    register-with-eureka: false #是否向注册中心注册自己
    fetch-registry: false #是否从Eureka获取注册信息
    service-url:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
  server: 
    wait-time-in-ms-when-sync-empty: 5 #在服务器接收请求之前等待的初始时间（分钟），用于生产配置
#    enable-self-preservation: false #自我保护是否启用
#    eviction-interval-timer-in-ms: 5000 #清理间隔

创建一个启动类代码如下：

package com.shareprog.eureka;

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

/**
 * @ClassName: EurekaApplication
 * @Description: Eureka启动类
 * @author cl
 * @date 2021年1月13日
 */
@SpringBootApplication
@EnableEurekaServer
public class EurekaApplication {

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

}

这样一个微服务注册中心就完成了。

如果上面配置文件中设置用户认证，那么还需要加配置，代码如下：

package com.shareprog.eureka.configuration;

import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.config.http.SessionCreationPolicy;

/**
 * @ClassName: WebSecurityConfig
 * @Description: 启用登录权限配置
 * @author cl
 * @date 2021年1月13日
 */
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

	@Override
	protected void configure(HttpSecurity http) throws Exception {
		/**
		 * 注意：为了可以使用 http://${user}:${password}@${host}:${port}/eureka/ 
		 * 这种方式登录,所以必须是httpBasic,
		 * 如果是form方式,不能使用url格式登录
		 */
		http.csrf().disable()
			.authorizeRequests().anyRequest().authenticated()
			.and().httpBasic()
			.and().sessionManagement().sessionCreationPolicy(SessionCreationPolicy.NEVER);
	}

}

这样项目就不会报错了。

如果有需求说，需要在服务注册或者服务宕机的时候进行处理，比如打印日志，发送邮件之类的，代码如下：

package com.shareprog.eureka.configuration;

import org.springframework.cloud.netflix.eureka.server.event.EurekaInstanceCanceledEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaInstanceRegisteredEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaInstanceRenewedEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaRegistryAvailableEvent;
import org.springframework.cloud.netflix.eureka.server.event.EurekaServerStartedEvent;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;

import com.netflix.appinfo.InstanceInfo;

import lombok.extern.slf4j.Slf4j;

@Component
@Slf4j
public class EurekaStateChangeListener {

	@EventListener
	public void listen(EurekaInstanceCanceledEvent event) {
		log.error(event.getServerId() + "\t" + event.getAppName() + " 服务下线 ");
	}

	@EventListener
	public void listen(EurekaInstanceRegisteredEvent event) {
		InstanceInfo instanceInfo = event.getInstanceInfo();
		log.error(instanceInfo.getAppName() + " 进行注册 ");
	}

	@EventListener
	public void listen(EurekaInstanceRenewedEvent event) {
		log.error(event.getServerId() + "\t" + event.getAppName() + " 服务进行续约 ");
	}

	@EventListener
	public void listen(EurekaRegistryAvailableEvent event) {
		log.error(" 注册中心启动 ");
	}

	@EventListener
	public void listen(EurekaServerStartedEvent event) {
		log.error("Eureka Server启动 ");
	}
}

Eureka集群

Eureka集群也很简单，只需要将搭建好的Eureka复制三份分别到不同的三台服务器上，修改不同的配置文件即可，三台服务配置如下：

Eureka1

server:
  port: 8001
spring:
  application:
    name: eureka
  security:
    user:
      name: eureka
      password: eureka
eureka:
  instance:
    hostname: 192.168.0.1 #UAT应用实例主机名
  client:
    register-with-eureka: false #是否向注册中心注册自己
    fetch-registry: false #是否从Eureka获取注册信息
    service-url:
      defaultZone: http://eureka:eureka@192.168.0.2:8001/eureka/,http://eureka:eureka@192.168.0.3:8001/eureka/

Eureka2

server:
  port: 8001
spring:
  application:
    name: eureka
  security:
    user:
      name: eureka
      password: eureka
eureka:
  instance:
    hostname: 192.168.0.2 #UAT应用实例主机名
  client:
    register-with-eureka: false #是否向注册中心注册自己
    lease-renewal-interval-in-seconds: 30  #服务续约任务的调用间隔时间，默认为30秒。
    lease-expiration-duration-in-seconds: 90 #服务失效的时间，默认为90秒。
    fetch-registry: false #是否从Eureka获取注册信息
    service-url:
      defaultZone: http://eureka:eureka@192.168.0.1:8001/eureka/,http://eureka:eureka@192.168.0.3:8001/eureka/

Eureka3

server:
  port: 8001
spring:
  application:
    name: eureka
  security:
    user:
      name: eureka
      password: eureka
eureka:
  instance:
    hostname: 192.168.0.3 #UAT应用实例主机名
  client:
    register-with-eureka: false #是否向注册中心注册自己
    fetch-registry: false #是否从Eureka获取注册信息
    service-url:
      defaultZone: http://eureka:eureka@192.168.0.1:8001/eureka/,http://eureka:eureka@192.168.0.2:8001/eureka/

获取其他服务的注册信息

	@Autowired
    private DiscoveryClient discoveryClient;

    public void getServiceInstances() {
        List<String> services = discoveryClient.getServices();
        for (String service : services) {
            List<ServiceInstance> instances = discoveryClient.getInstances(service);
            for (ServiceInstance instance : instances) {
                EurekaDiscoveryClient.EurekaServiceInstance eurekaServiceInstance = (EurekaDiscoveryClient.EurekaServiceInstance)instance;
                InstanceInfo instanceInfo = eurekaServiceInstance.getInstanceInfo();
                System.out.println(JSON.toJSONString(instanceInfo));
            }
        }
    }

自定义元数据

eureka:
  instance:
    metadata-map:
      test: "test"

在上面获取注册信息的时候使用

System.out.println(instanceInfo.getMetadata().get("test"));