Eureka集群部署以及踩坑记录（实例始终unavailable）一、Eureka集群部署二、集群部署时可能遇到的坑三、总结

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我是靠谱客的博主风趣香水，最近开发中收集的这篇文章主要介绍Eureka集群部署以及踩坑记录（实例始终unavailable）一、Eureka集群部署二、集群部署时可能遇到的坑三、总结，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

一、Eureka集群部署

建议先严格按照步骤来部署，不然容易出问题，可能出现的问题会在下边说明

1、新建一个maven工程，pom示例如下

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.iceberg.eurekatest</groupId>
<artifactId>eureka-test</artifactId>
<version>1.0-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Greenwich.SR2</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<!-- spring -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>

2、在Application类上加上注解，开启eureka

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

3、添加两个配置文件 application-peer1.yaml

spring:
application:
name: eureka-server
server:
port: 8001
eureka:
client:
#是否将自己注册到Eureka Server
register-with-eureka: true
#是否从Eureka Server获取注册信息
fetch-registry: true
serviceUrl:
defaultZone: "http://peer2:8002/eureka/"
instance:
prefer-ip-address: false
hostname: "peer1"

application-peer2.yaml

spring:
application:
name: eureka-server
server:
port: 8002
eureka:
client:
#是否将自己注册到Eureka Server
register-with-eureka: true
#是否从Eureka Server获取注册信息
fetch-registry: true
serviceUrl:
defaultZone: "http://peer1:8001/eureka/"
instance:
prefer-ip-address: false
hostname: "peer2"

4、在host中添加两条映射
127.0.0.1 peer1
127.0.0.1 peer2

5、在SpringBoot的启动参数上加上-Dspring.profiles.active=peer1，然后启动项目。

然后改成peer2，启动项目（共启动两个）

6、注意事项
（1）在启动第一个eureka的时候，会报下列异常

2019-07-29 15:49:57.335
WARN 15416 --- [nfoReplicator-0] c.n.discovery.InstanceInfoReplicator
: There was a problem with the instance info replicator
com.netflix.discovery.shared.transport.TransportException: Cannot execute request on any known server
at com.netflix.discovery.shared.transport.decorator.RetryableEurekaHttpClient.execute(RetryableEurekaHttpClient.java:112) ~[eureka-client-1.9.12.jar:1.9.12]
at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.register(EurekaHttpClientDecorator.java:56) ~[eureka-client-1.9.12.jar:1.9.12]
at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator$1.execute(EurekaHttpClientDecorator.java:59) ~[eureka-client-1.9.12.jar:1.9.12]
at com.netflix.discovery.shared.transport.decorator.SessionedEurekaHttpClient.execute(SessionedEurekaHttpClient.java:77) ~[eureka-client-1.9.12.jar:1.9.12]
at com.netflix.discovery.shared.transport.decorator.EurekaHttpClientDecorator.register(EurekaHttpClientDecorator.java:56) ~[eureka-client-1.9.12.jar:1.9.12]
at com.netflix.discovery.DiscoveryClient.register(DiscoveryClient.java:847) ~[eureka-client-1.9.12.jar:1.9.12]
at com.netflix.discovery.InstanceInfoReplicator.run(InstanceInfoReplicator.java:121) ~[eureka-client-1.9.12.jar:1.9.12]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_212]
at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266) [na:1.8.0_212]
at java.util.concurrent.FutureTask.run(FutureTask.java) [na:1.8.0_212]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_212]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [na:1.8.0_212]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_212]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_212]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_212]

这个异常的意思是配置的eureka-server未找到（因为你还没启动），当第二个eureka-server启动好之后就正常了
（2）在eureka单机版配置中，register-with-eureka和fetch-registry 这两个选项是false，但是集群版的eureka是利用服务发现来实现的，所以需要改成true来向服务端注册自己并获取客户端信息
7、启动完成后，浏览器访问localhost:8001和localhost:8002
看到下图表示成功

二、集群部署时可能遇到的坑

1、不想加host，直接使用localhost
有些朋友可能不知道怎么改host或者干脆就是懒，直接用localhost取代之前的peer1和peer2，配置文件如下
application-peer1.yaml

spring:
application:
name: eureka-server
server:
port: 8001
eureka:
client:
#是否将自己注册到Eureka Server
register-with-eureka: true
#是否从Eureka Server获取注册信息
fetch-registry: true
serviceUrl:
defaultZone: "http://localhost:8002/eureka/"
instance:
prefer-ip-address: false
hostname: "localhost"

application-peer2.yaml

spring:
application:
name: eureka-server
server:
port: 8002
eureka:
client:
#是否将自己注册到Eureka Server
register-with-eureka: true
#是否从Eureka Server获取注册信息
fetch-registry: true
serviceUrl:
defaultZone: "http://localhost:8001/eureka/"
instance:
prefer-ip-address: false
hostname: "localhost"

这里分成两种情况：
（1）单机部署两个eureka，然后访问http://localhost:8001/
可以看到registered-replicas那一栏为空了，为什么会这样子？
我们来看下eureka的源码中PeerEurekaNodes的resolvePeerUrls()方法，这个方法的作用是从配置的serviceUrl中获取可用的地址

protected List<String> resolvePeerUrls() {
InstanceInfo myInfo = applicationInfoManager.getInfo();
String zone = InstanceInfo.getZone(clientConfig.getAvailabilityZones(clientConfig.getRegion()), myInfo);
List<String> replicaUrls = EndpointUtils
.getDiscoveryServiceUrls(clientConfig, zone, new EndpointUtils.InstanceInfoBasedUrlRandomizer(myInfo));
int idx = 0;
while (idx < replicaUrls.size()) {
//这个地方就是罪魁祸首
if (isThisMyUrl(replicaUrls.get(idx))) {
replicaUrls.remove(idx);
} else {
idx++;
}
}
return replicaUrls;
}
public boolean isThisMyUrl(String url) {
final String myUrlConfigured = serverConfig.getMyUrl();
if (myUrlConfigured != null) {
return myUrlConfigured.equals(url);
}
return isInstanceURL(url, applicationInfoManager.getInfo());
}
//判断url的hostnam和当前的hostname是否一致，如果一致则直接忽略
public boolean isInstanceURL(String url, InstanceInfo instance) {
String hostName = hostFromUrl(url);
String myInfoComparator = instance.getHostName();
if (clientConfig.getTransportConfig().applicationsResolverUseIp()) {
myInfoComparator = instance.getIPAddr();
}
return hostName != null && hostName.equals(myInfoComparator);
}

通过isInstanceURL()方法，eureka会把hostname相同的url移除掉，而恰好我们配置的都是localhost，所以虽然你启动了两个eureka，但是它们不会把自己当成集群
（2）多机（或者多个虚拟机）部署
如果你把两个eureka启动在了不同的主机上，并配置了localhost，那你会一直看到com.netflix.discovery.shared.transport.TransportException: Cannot execute request on any known server这个错误，因为它无法通过localhost找到另一个eureka

2、不使用域名，而是使用IP注册
eureka提供了一个选项，可以使eureka注册的地址不使用域名而是IP，配置项是eureka.instance.prefer-ip-address=true
（1）单机多网卡部署
这里解释一下什么是多网卡，我们安装vmware之后，它会给我们创建一些虚拟网卡，比如我这边它就给我创建了两个虚拟地址

多网卡的意思是你使用ipconfig命令，能看到多个IP地址（只是我自己的定义，不代表学术定义）
这种情况下eureka注册的IP跟你实际的IP可能是不同的，比如我刚才启动的eureka它的instance info显示的IP就是 192.168.157.1，这种情况下他注册的IP也是192.168.157.1，为了让他注册实际的IP，我们需要通过 eureka.instance.ip-address=10.60.44.136指定一下
然后问题就来了，假如你的peer1填的ip-address是10.60.44.136，peer2中的serviceUrl.defaultZone中的url也得是10.60.44.136，那peer2的ip-address用啥呢？也用10.60.44.136的话就会出现之前的问题，被eureka自己排除掉，所以你需要换一个IP且仍然表示本地的，比如127.0.0.1，配置文件如下所示： application-peer1.yaml

spring:
application:
name: eureka-server
server:
port: 8001
eureka:
client:
#是否将自己注册到Eureka Server
register-with-eureka: true
#是否从Eureka Server获取注册信息
fetch-registry: true
serviceUrl:
defaultZone: "http://127.0.0.1:8002/eureka/"
instance:
prefer-ip-address: true
hostname: "localhost"
ip-address: "10.60.44.136"

application-peer2.yaml

spring:
application:
name: eureka-server
server:
port: 8002
eureka:
client:
#是否将自己注册到Eureka Server
register-with-eureka: true
#是否从Eureka Server获取注册信息
fetch-registry: true
serviceUrl:
defaultZone: "http://10.60.44.136:8001/eureka/"
instance:
prefer-ip-address: true
hostname: "localhost"
ip-address: "127.0.0.1"

运行后的结果如下图