Spring Cloud(Finchley版本)系列教程(一) 服務注冊與發(fā)現(xiàn)(eureka)

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一、構(gòu)建環(huán)境

Spring Cloud的構(gòu)建工具可以使用Maven或Gradle，但Maven任然是主流。本文檔所使用的開發(fā)環(huán)境如下：

Spring Cloud相關(guān)模塊

但Spring Cloud主要有5大組件，分別為服務發(fā)現(xiàn)組件Eureka、Feign、Ribbon、Zuul、Hystrix。但很多都棄用了，比如Ribbon等。

注：SpringCloud版本說明

二、微服務注冊與發(fā)現(xiàn)

Spring Cloud提供了很多服務發(fā)現(xiàn)組件，比如：Eureka、Consul、ZooKeeper等。而Eureka是Netflix開源的服務發(fā)現(xiàn)組件，它包含Server和Client兩部分。Eureka Server提供服務發(fā)現(xiàn)的能力，每個微服務啟動時，都會向Eureka Server注冊自己的信息(IP、端口、微服務名稱等)，Eureka Server存儲記錄每個微服務的這些信息。Eureka Client是用于簡化與Eureka Server交互的Java客戶端。微服務啟動后，會周期性地(默認30s)向Eureka Server發(fā)送心跳以續(xù)約自己的可用時間。如果Eureka Server在規(guī)定的時間內(nèi)沒有接收到微服務實例的心跳，Eureka Server則會將該實例注銷(默認90s)。

常見的注冊中心

2.1 創(chuàng)建EurekaServer

在idea中，創(chuàng)建一個名稱為eurekaServer的Maven工程。

pom.xml文件增加Eureka依賴，修改SpringCloud版本為Finchley.SR2，修改SpringBoot版本為2.0.6.RELEASE。

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cc.huerpu</groupId>
    <artifactId>eurekaServer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eurekaServer</name>
    <description>eurekaServer</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR2</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.SR2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

修改EurekaServerApplication啟動類，增加@EnableEurekaServer注解。

package cc.huerpu.eurekaserver;

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

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {

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

}

創(chuàng)建application.yml文件

server:
  port: 8761 # 端口號

spring:
  application:
    name: eurekaServer # Eureka名稱

eureka:
  instance:
    prefer-ip-address: false
    hostname: eurekaServer
  client:
    fetch-registry: false # 表示是否從EurekaServer獲取注冊信息，默認為true。因為本應用是一個單點的EurekaServer，不需要同步其他的EurekaServer節(jié)點的數(shù)據(jù)，因此設(shè)為false。
    register-with-eureka: false # 是否將自己注冊到EurekaServer，默認為true。由于當前應用就是EurekaServer，因此設(shè)為false。
    service-url:
      defaultZone: http://eurekaServer:8761/eureka/

修改系統(tǒng)的hosts，Windows11的hosts文件路徑為：C:\Windows\System32\drivers\etc\hosts。Linux和macOS的文件路徑為/etc/hosts。增加一行：127.0.0.1 eurekaServer。

啟動項目，并測試訪問

點擊idea的項目啟動按鈕，并訪問http://eurekaserver:8761/查看Eureka首頁。

2.2 創(chuàng)建EurekaClient，并讓它注冊到EurekaServer上。

復制eurekaServer項目，修改artifactId為EurekaClient。修改application.yml文件，端口號為8000，應用名稱為eurekaClient。

server:
  port: 8000 # 端口號

spring:
  application:
    name: eurekaClient # Eureka名稱

management:
  info:
    env:
      enabled: true
  endpoints:
    web:
      exposure:
        include: "*"
    enabled-by-default: true

eureka:
  instance:
    prefer-ip-address: false
    hostname: eurekaClient
  client:
    healthcheck:
      enabled: true
    fetch-registry: true 
    register-with-eureka: true 
    service-url:
      defaultZone: http://eurekaServer:8761/eureka/

修改啟動類，增加@EnableDiscoveryClient注解。

package cc.huerpu.eurekaclient;


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

@SpringBootApplication
@EnableDiscoveryClient
public class EurekaClientApplication {

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

}

編寫一個測試接口，最簡單的那種就好。

@RestController
public class UserController {

    @RequestMapping("/getUserById")
    public String getUserById(){

        return "{id:1,name:jason,age:23}";
    }

}

修改pom.xml文件，把幾處地方改為eurekaClient，另外增加了一個actuator包。

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cc.huerpu</groupId>
    <artifactId>eurekaClient</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eurekaClient</name>
    <description>eurekaClient</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR2</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.SR2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

啟動項目，刷新http://eurekaClient:8761/會看到EurekaClient注冊上來了。

2.3 添加EurekaServer用戶認證

在實際應用中，資源的訪問都是需要認證的，接下來我們把EurekaServer 改造為需要認證的服務。

EurekaServer 添加security依賴：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

修改EurekaServer的application.yml文件，增加security認證，增加spring.security.user.name和spring.security.user.password。并修改defaultZone為http://eurekaha:eurekapwd@eurekaServer:8761/eureka/。

server:
  port: 8761 # 端口號

spring:
  security:
    user:
      name: eureka
      password: eurekapwd
  application:
    name: eurekaServer # Eureka名稱

eureka:
  instance:
    prefer-ip-address: false
    hostname: eurekaServer
  client:
    fetch-registry: true
    register-with-eureka: true
    service-url:
      defaultZone: http://eureka:eurekapwd@eurekaServer:8761/eureka/

在EurekaServer的cc.huerpu.eurekaserver.security包路徑下創(chuàng)建WebSecurityConfig類，關(guān)閉csrf，并開啟httpBasic認證。

package cc.huerpu.eurekaserver.security;

import org.springframework.context.annotation.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;

@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable();
        http.authorizeRequests()
            .anyRequest()
            .authenticated()
            .and()
            .httpBasic();
    }
}

重新啟動項目，訪問時需要認證登錄。

輸入配置文件里的賬號/密碼：eureka/eurekapwd進行登錄。

如果你的沒有注冊上來，耐心等一分鐘就可以了。

對于創(chuàng)建Eureka的注冊中心集群，請參考文章：http://www.huerpu.cc:7000/?p=607。這里就不做過多的介紹了。

三、創(chuàng)建一個eurekaClientConsumer調(diào)用eurekaClient服務

復制eurekaClient項目，修改artifactId為eurekaClientConsumer。修改application.yml文件，端口號為8001，應用名稱為eurekaClientConsumer(本機host中也增加這一個)。

127.0.0.1   localhost
127.0.0.1   eurekaServer
127.0.0.1   eurekaClient
127.0.0.1   eurekaclientconsumer

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cc.huerpu</groupId>
    <artifactId>eurekaClientConsumer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eurekaClientConsumer</name>
    <description>eurekaClientConsumer</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR2</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Finchley.SR2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.yml

server:
  port: 8001 # 端口號

spring:
  application:
    name: eurekaClientConsumer # Eureka名稱


management:
  info:
    env:
      enabled: true
  endpoints:
    web:
      exposure:
        include: "*"
    enabled-by-default: true

eureka:
  instance:
    prefer-ip-address: false
    hostname: eurekaClientConsumer
  client:
    healthcheck:
      enabled: true
    fetch-registry: true
    register-with-eureka: true
    service-url:
      defaultZone: http://eureka:eurekapwd@eurekaServer:8761/eureka/

修改啟動類名稱為EurekaClientConsumerApplication，并增加注入一個restTemplate。

package cc.huerpu.eurekaclient;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class EurekaClientConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(EurekaClientConsumerApplication.class, args);
    }
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

在controller包下創(chuàng)建一個ConsumerController類，注入restTemplate、eurekaClient、discoveryClient。

package cc.huerpu.eurekaclient.controller;

import com.netflix.appinfo.InstanceInfo;
import com.netflix.discovery.EurekaClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import java.util.List;

@RestController
public class ConsumerController {
    @Autowired
    private RestTemplate  restTemplate;
    @Autowired
    private EurekaClient eurekaClient;

    @Autowired
    private DiscoveryClient discoveryClient;

    //獲得eurekaClient的url
    @RequestMapping("/eurekaClientServiceUrl")
    private String eurekaClientServiceUrl() {
        InstanceInfo instance = eurekaClient.getNextServerFromEureka("eurekaClient", false);
        return instance.getHomePageUrl();
    }

    @RequestMapping("/consumerEurekaClient")
    public String consumerEurekaClient(){
        String eurekaClientURL = eurekaClientServiceUrl();
        String res = restTemplate.getForObject(eurekaClientURL + "/getUserById",String.class);
        return "consumerEurekaClient:" + res;
    }

    @RequestMapping("/eurekaClient-instance")
    public List<ServiceInstance> showInfo() {
        return this.discoveryClient.getInstances("eurekaClient");
    }
}

在沒有服務注冊中心的時候，eurekaClientConsumer服務調(diào)用eurekaClient服務，需要在eurekaClientConsumer服務代碼里顯式通過硬編碼IP地址和端口號進行調(diào)用，也可以通過@Value注入配置的方式進行配置，但被調(diào)用方方的IP和端口號變化之后，調(diào)用方就必須進行修改，針對千千萬萬的接口來說，維護這些信息簡直是場噩夢。

@RestController
public class ConsumerController {

    @RequestMapping("/consumerEurekaClient")
    public String consumerEurekaClient(){
        String res = restTemplate.getForObject("http://localhost:8000/getUserById", String.class);
        return "consumerEurekaClient:" + res;
    }
  
}

@RestController
public class ConsumerController {
		//通過配置文件中的hep.eurekaclient.userservice.url值進行配置
    @Value("${hep.eurekaclient.userservice.url}")
    private String eurekaClient;
    @RequestMapping("/consumerEurekaClient")
    public String consumerEurekaClient(){
        String res = restTemplate.getForObject("http://localhost:8000/getUserById", String.class);
        return "consumerEurekaClient:" + res;
    }
}

但現(xiàn)在我們通過eureka就沒有這個煩惱啦，只需要eurekaClient.getNextServerFromEureka("eurekaClient", false)，就可以獲得服務的調(diào)用地址，其中"eurekaClient"是由spring.application.name指定的，即使被調(diào)用方的IP和端口號變化，對我們來說都是無感的，調(diào)用方這邊完全不用做任何修改，是不是很開心？

訪問http://eurekaclientconsumer:8001/consumerEurekaClient，就可以得到consumerEurekaClient:{id:1,name:jason,age:23}，證明我們的消費方consumerEurekaClient調(diào)用被消費方eurekaClient成功了。

四、Eureka 的元數(shù)據(jù)

Eureka 的元數(shù)據(jù)有兩種，標準元數(shù)據(jù)和自定義元數(shù)據(jù)。標準元數(shù)據(jù)有主機名、IP地址、端口號、狀態(tài)頁和健康檢查等信息，這些信息都會被發(fā)布在服務注冊表中，用于服務之間的調(diào)用。自定義元數(shù)據(jù)可以使用eureka.instance.metadata-map配置。

可以通過http://eurekaserver:8761/eureka/apps來查看eureka中有哪些應用。

<applications>
	<versions__delta>1</versions__delta>
	<apps__hashcode>UP_3_</apps__hashcode>
	<application>
		<name>EUREKASERVER</name>
		<instance>
			<instanceId>localhost:eurekaServer:8761</instanceId>
			<hostName>eurekaServer</hostName>
			<app>EUREKASERVER</app>
			<ipAddr>192.168.75.1</ipAddr>
			<status>UP</status>
			<overriddenstatus>UNKNOWN</overriddenstatus>
			<port enabled="true">8761</port>
			<securePort enabled="false">443</securePort>
			<countryId>1</countryId>
			<dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
				<name>MyOwn</name>
			</dataCenterInfo>
			<leaseInfo>
				<renewalIntervalInSecs>30</renewalIntervalInSecs>
				<durationInSecs>90</durationInSecs>
				<registrationTimestamp>1693982763311</registrationTimestamp>
				<lastRenewalTimestamp>1693984895889</lastRenewalTimestamp>
				<evictionTimestamp>0</evictionTimestamp>
				<serviceUpTimestamp>1693982734094</serviceUpTimestamp>
			</leaseInfo>
			<metadata>
				<management.port>8761</management.port>
			</metadata>
			<homePageUrl>http://eurekaServer:8761/</homePageUrl>
			<statusPageUrl>http://eurekaServer:8761/actuator/info</statusPageUrl>
			<healthCheckUrl>http://eurekaServer:8761/actuator/health</healthCheckUrl>
			<vipAddress>eurekaServer</vipAddress>
			<secureVipAddress>eurekaServer</secureVipAddress>
			<isCoordinatingDiscoveryServer>true</isCoordinatingDiscoveryServer>
			<lastUpdatedTimestamp>1693982763311</lastUpdatedTimestamp>
			<lastDirtyTimestamp>1693982733236</lastDirtyTimestamp>
			<actionType>ADDED</actionType>
		</instance>
	</application>
	<application>
		<name>EUREKACLIENT</name>
		<instance>
			<instanceId>localhost:eurekaClient:8000</instanceId>
			<hostName>eurekaClient</hostName>
			<app>EUREKACLIENT</app>
			<ipAddr>192.168.75.1</ipAddr>
			<status>UP</status>
			<overriddenstatus>UNKNOWN</overriddenstatus>
			<port enabled="true">8000</port>
			<securePort enabled="false">443</securePort>
			<countryId>1</countryId>
			<dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
				<name>MyOwn</name>
			</dataCenterInfo>
			<leaseInfo>
				<renewalIntervalInSecs>30</renewalIntervalInSecs>
				<durationInSecs>90</durationInSecs>
				<registrationTimestamp>1693982763312</registrationTimestamp>
				<lastRenewalTimestamp>1693984884241</lastRenewalTimestamp>
				<evictionTimestamp>0</evictionTimestamp>
				<serviceUpTimestamp>1693982751862</serviceUpTimestamp>
			</leaseInfo>
			<metadata>
				<management.port>8000</management.port>
			</metadata>
			<homePageUrl>http://eurekaClient:8000/</homePageUrl>
			<statusPageUrl>http://eurekaClient:8000/actuator/info</statusPageUrl>
			<healthCheckUrl>http://eurekaClient:8000/actuator/health</healthCheckUrl>
			<vipAddress>eurekaClient</vipAddress>
			<secureVipAddress>eurekaClient</secureVipAddress>
			<isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
			<lastUpdatedTimestamp>1693982763312</lastUpdatedTimestamp>
			<lastDirtyTimestamp>1693982751816</lastDirtyTimestamp>
			<actionType>ADDED</actionType>
		</instance>
	</application>
	<application>
		<name>EUREKACLIENTCONSUMER</name>
		<instance>
			<instanceId>localhost:eurekaClientConsumer:8001</instanceId>
			<hostName>eurekaClientConsumer</hostName>
			<app>EUREKACLIENTCONSUMER</app>
			<ipAddr>192.168.75.1</ipAddr>
			<status>UP</status>
			<overriddenstatus>UNKNOWN</overriddenstatus>
			<port enabled="true">8001</port>
			<securePort enabled="false">443</securePort>
			<countryId>1</countryId>
			<dataCenterInfo class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
				<name>MyOwn</name>
			</dataCenterInfo>
			<leaseInfo>
				<renewalIntervalInSecs>30</renewalIntervalInSecs>
				<durationInSecs>90</durationInSecs>
				<registrationTimestamp>1693984674119</registrationTimestamp>
				<lastRenewalTimestamp>1693984884145</lastRenewalTimestamp>
				<evictionTimestamp>0</evictionTimestamp>
				<serviceUpTimestamp>1693984674119</serviceUpTimestamp>
			</leaseInfo>
			<metadata>
				<management.port>8001</management.port>
			</metadata>
			<homePageUrl>http://eurekaClientConsumer:8001/</homePageUrl>
			<statusPageUrl>http://eurekaClientConsumer:8001/actuator/info</statusPageUrl>
			<healthCheckUrl>http://eurekaClientConsumer:8001/actuator/health</healthCheckUrl>
			<vipAddress>eurekaClientConsumer</vipAddress>
			<secureVipAddress>eurekaClientConsumer</secureVipAddress>
			<isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
			<lastUpdatedTimestamp>1693984674119</lastUpdatedTimestamp>
			<lastDirtyTimestamp>1693984674059</lastDirtyTimestamp>
			<actionType>ADDED</actionType>
		</instance>
	</application>
</applications>

我們在上面也有寫了一個接口，用來獲得eurekaClient服務的相關(guān)實例。

@Autowired
private DiscoveryClient discoveryClient;

@RequestMapping("/eurekaClient-instance")
public List<ServiceInstance> showInfo() {
    return this.discoveryClient.getInstances("eurekaClient");
}

<List>
	<item>
		<host>eurekaClient</host>
		<port>8000</port>
		<metadata>
			<management.port>8000</management.port>
		</metadata>
		<secure>false</secure>
		<uri>http://eurekaClient:8000</uri>
		<serviceId>EUREKACLIENT</serviceId>
		<instanceInfo>
			<instanceId>localhost:eurekaClient:8000</instanceId>
			<app>EUREKACLIENT</app>
			<appGroupName />
			<ipAddr>192.168.75.1</ipAddr>
			<sid>na</sid>
			<homePageUrl>http://eurekaClient:8000/</homePageUrl>
			<statusPageUrl>http://eurekaClient:8000/actuator/info</statusPageUrl>
			<healthCheckUrl>http://eurekaClient:8000/actuator/health</healthCheckUrl>
			<secureHealthCheckUrl />
			<vipAddress>eurekaClient</vipAddress>
			<secureVipAddress>eurekaClient</secureVipAddress>
			<countryId>1</countryId>
			<dataCenterInfo _class="com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo">
				<name>MyOwn</name>
			</dataCenterInfo>
			<hostName>eurekaClient</hostName>
			<status>UP</status>
			<overriddenStatus>UNKNOWN</overriddenStatus>
			<leaseInfo>
				<renewalIntervalInSecs>30</renewalIntervalInSecs>
				<durationInSecs>90</durationInSecs>
				<registrationTimestamp>1693982763312</registrationTimestamp>
				<lastRenewalTimestamp>1693984674011</lastRenewalTimestamp>
				<evictionTimestamp>0</evictionTimestamp>
				<serviceUpTimestamp>1693982751862</serviceUpTimestamp>
			</leaseInfo>
			<isCoordinatingDiscoveryServer>false</isCoordinatingDiscoveryServer>
			<metadata>
				<management.port>8000</management.port>
			</metadata>
			<lastUpdatedTimestamp>1693982763312</lastUpdatedTimestamp>
			<lastDirtyTimestamp>1693982751816</lastDirtyTimestamp>
			<actionType>ADDED</actionType>
			<asgName />
		</instanceInfo>
		<scheme />
	</item>
</List>

五、Eureka的健康檢查

在pom文件中引入Spring Boot Actuator，它提供了/health端點，該端點可展示應用程序的健康信息。

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

引入Actuator后，在Eureka中開啟健康檢查。

eureka:
  client:
    healthcheck:
      enabled: true 	 #開啟健康檢查(依賴spring-boot-actuator)

訪問http://localhost:8761/actuator/health可以查看Eureka的狀態(tài)。

若出現(xiàn)下面紅色警告，其實是Eureka進入自我保護模式。如果最近一分鐘實際接收到的心跳值Renews除以期望的心跳閾值 Renews threshold小于等于0.85，即 Renews/Renews threshold≤0.85。

EMERGENCY! EUREKA MAY BE INCORRECTLY CLAIMING INSTANCES ARE UP WHEN THEY’RE NOT. RENEWALS ARE LESSER THAN THRESHOLD AND HENCE THE INSTANCES ARE NOT BEING EXPIRED JUST TO BE SAFE

可以把renewal-percent-threshold調(diào)的小一些

eureka:
  server:
    renewal-percent-threshold: 0.49

或者暴力一點關(guān)閉自我保護模式

# 默認值是true
eureka:
  server:
  	enable-self-preservation: false

默認情況下，服務注冊到Eureka Server的過程較慢。在開發(fā)或測試時，常常希望能夠加速這一過程，從而提升工作效率。

##默認是30，單位秒。設(shè)成一個更小的值，該配置用于設(shè)置Eureka Client向Eureka Server發(fā)送心跳的時間間隔
eureka:
  instance:
    lease-renewal-interval-in-seconds: 5

本文參考SpringCloud官方文檔：https://docs.spring.io/spring-cloud-netflix/docs/4.0.1/reference/html/

六、部署eurekaserver到ubuntu22.04服務器

每次都啟動eureka的項目，太繁瑣了，我們把eureka部署到Ubuntu，就可以愉快的玩耍了。最好部署到一臺可以遠程訪問的服務器，這樣在任何地方都可以注冊服務和消費服務了。

6.1 配置文件設(shè)置

這里為了演示，我們準備好了一臺 ubuntu22.04，IP地址為192.168.169.128 。

在eurekaserver項目，創(chuàng)建application-text.yml文件，內(nèi)容如下

server:
  port: 8761 # 端口號

spring:
  security:
    user:
      name: eureka
      password: eurekapwd
  application:
    name: eurekaServer # Eureka名稱

eureka:
  server:
    enable-self-preservation: true
  instance:
    prefer-ip-address: ture
  client:
    fetch-registry: true
    register-with-eureka: true
    service-url:
      defaultZone: http://eureka:eurekapwd@192.168.169.128:8761/eureka/

application.properties中增加讓test生效配置。

spring.profiles.active=test

6.2 生成eurekaserver的jar包

生成eurekaserver的jar包：

6.3 ubuntu安裝jdk1.8

sudo su -

apt update

apt upgrade -y

apt install openjdk-8-jre-headless

java -version

6.4 運行eurekaServer-0.0.1-SNAPSHOT.jar包

我們把eurekaServer-0.0.1-SNAPSHOT.jar包 放在/usr/software目錄下，根據(jù)個人喜好目錄存放即可。使用MobaXterm等SSH工具上傳即可。

cd /usr
#創(chuàng)建software文件夾，在此文件夾下有我們的eurekaServer-0.0.1-SNAPSHOT.jar包，可以通過上傳工具上傳過來
mkdir software
#賦予權(quán)限
chmod -R 777 software
#進入到software目錄
cd software

#運行jar包
nohup java -jar eurekaServer-0.0.1-SNAPSHOT.jar > log.txt &

#開放8761端口
ufw allow 8761
ufw enable

6.5 驗證eurekaserver服務

打開http://192.168.169.128:8761/查看，Eureka已經(jīng)啟動了。

把eurekaClient項目修改defaultZone為http://eureka:eurekapwd@192.168.169.128:8761/eureka/，prefer-ip-address改為true

defaultZone: http://eureka:eurekapwd@192.168.169.128:8761/eureka/
prefer-ip-address: true

重啟eurekaClient項目，并刷新eurekaserver，查看服務是否注冊上來。

七、eureka相關(guān)說明

7.1 EurekaServer REST API接口

POST    /eureka/apps/{appId}                                            注冊新的實例

DELETE  /eureka/apps/{appId}/{instanceId}                               注銷應用實例

PUT     /eureka/apps/{appId}/{instanceId}                               應用實例發(fā)送心跳

GET     /eureka/apps                                                    查詢所有的實例

GET     /eureka/apps/{appId}                                            查詢指定appId的實例

GET     /eureka/apps/{appId}/{instanceId}                               查詢指定appId和instanceId的實例

GET     /eureka/instances/{instanceId}                                  查詢指定的instanceId的實例

PUT     /eureka/apps/{appId}/{instanceId}/status?value=OUT_OF_SERVICE   暫停應用實例

PUT     /eureka/apps/{appId}/{instanceId}/status?value=UP               恢復應用實例

PUT     /eureka/apps/{appId}/{instanceId}/metadata?key=value            更新元數(shù)據(jù)信息

GET     /eureka/vips/{vipAddress}                                       根據(jù)vip地址查詢

GET     /eureka/svips/{svipAddress}                                     根據(jù)svip地址查詢

7.2 Client端參數(shù)

eureka.client.register-with-eureka: true                     是否注冊自己到Eureka Server上面
eureka.client.fetch-registry: true                           是否從Eureka Server上面拉取服務信息
eureka.client.enable: true                                   是否啟用Eureka客戶端,不啟用則不注冊到Eureka Server
eureka.client.healthcheck.enable: true                       是否啟用Eureka健康檢查
eureka.client.availability-zones: new HashMap<>()            告訴client有哪些可用的region和zone
eureka.client.filter-only-up-instances: true                 是否過濾出InstanceStatus為UP的實例
eureka.client.region: us-east-1                              指定該應用實例所在的region,AWS datacenters適用
eureka.client.prefer-same-zone-eureka: true                  是否優(yōu)先使用與該應用相同Zone的Eureka Server
eureka.client.cache-refresh-executor-thread-pool-size: 2     緩存刷新線程池CacheRefreshThread的初始化線程數(shù)
eureka.client.registry-fetch-interval-seconds: 30            Eureka client拉取服務注冊信息間隔時間(s)
eureka.client.instance-info-replication-interval-seconds: 30 復制實例變化信息到Eureka服務器所需要的時間間隔（s）
eureka.client.eureka-service-url-poll-interval-seconds:  300 輪詢Eureka服務端地址更改的間隔時間(s)
eureka.client.eureka-server-read-timeout-seconds: 8          讀取Eureka Server信息的超時時間(s)
eureka.client.eureka-server-connect-timeout-seconds: 5       連接Eureka Server的超時時間(s)
eureka.client.eureka-server-total-connections: 200           從Eureka客戶端到所有Eureka服務端的連接總數(shù)
eureka.client.eureka-server-total-connections-per-host: 50   從Eureka客戶端到每個Eureka服務端主機的連接總數(shù)
eureka.client.eureka-connection-idle-timeout-seconds: 30     Eureka服務端連接的空閑關(guān)閉時間(s)
eureka.instance.metadata-map: new HashMap<>()                指定應用實例的元數(shù)據(jù)信息
eureka.instance.prefer-ip-address: false                     是否優(yōu)先使用ip地址來替代hostname作為實例hostname字段值 
eureka.instance.lease-expiration-duration-in-seconds: 90     Eureka clent最后一次心跳后,Eureka Server剔除需要等待時間(s)
eureka.instance.lease-renewal-interval-in-seconds: 30        客戶端向Eureka Server發(fā)送心跳周期(s)

7.3 Server端參數(shù)

eureka.server.enable-self-preservation: true                 Eureka Server是否開啟自我保護模式
eureka.server.renewal-percent-threshold: 0.85                指定每分鐘需要收到的續(xù)約次數(shù)的闕值,如果閾值比最小值大,則自我保護模式開啟
eureka.server.eviction-interval-timer-in-ms: 60*1000         指定EvictionTask定時任務的調(diào)度頻率,用于剔除過期的實例
eureka.server.wait-time-in-ms-when-sync-empty: 1000*60*5     在Eureka服務器獲取不到集群里對等服務器上的實例時，需要等待的時間

八、代碼地址

代碼共享地址：http://www.huerpu.cc:2080/root/springcloud-finchley文章來源地址http://www.zghlxwxcb.cn/news/detail-704379.html

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