spring-cloud - FeignClient 无法解析 Eureka 服务名称

Question

我正在使用 spring-cloud-starter-openfeign 编写 Eureka 客户端应用程序客户。
这是我的聚甲醛

<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>2.2.4.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>service-registration-and-discovery-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>service-registration-and-discovery-client</name>
<description>Demo project for Spring Boot</description>

<properties>
    <java.version>1.8</java.version>
    <spring-cloud.version>Hoxton.SR1</spring-cloud.version>
</properties>

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

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</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>

如您所见，我使用的是spring boot版本 2.2.4.RELEASEspring-cloud.version Hoxton.SR1
这是我的应用程序类:

@SpringBootApplication
@EnableFeignClients
public class ServiceRegistrationAndDiscoveryClientApplication {

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

}

直到这里我的客户端应用程序在 Eureka 服务上成功注册，我也可以在 Eureka 页面上看到我的应用程序。

现在我已经编写了一个接口(interface)来调用另一个服务，该服务也在 Eureka 上注册，

@FeignClient("ANOTHER-SERVICE")
public interface SPProxy {

    @PostMapping("/anotherserviceplatform/api/resource/test")
    String testAPI(@RequestBody TestRequestBody request);
}

我正在从我的一个 Controller 中调用此方法。但 Feign 没有将服务名称解析为它的 URL。尝试进行 http 调用

http://ANOTHER-SERVICE/anotherservice/api/resource/test

而不是打电话

http://192.168.1.1:8080/anotherservice/api/resource/test

并获得超时异常(这很明显)。下面是堆栈跟踪

2020-01-31 13:03:56.281 ERROR 16693 --- [nio-8080-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is feign.RetryableException: connect timed out executing POST http://ANOTHER-SERVICE/anotherservice/api/resource/test] with root cause

java.net.SocketTimeoutException: connect timed out
    at java.base/java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:na]
    at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399) ~[na:na]
    at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242) ~[na:na]
    at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224) ~[na:na]
    at java.base/java.net.Socket.connect(Socket.java:591) ~[na:na]
    at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:177) ~[na:na]
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474) ~[na:na]
    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569) ~[na:na]
    at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:na]
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341) ~[na:na]
    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362) ~[na:na]
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1248) ~[na:na]
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187) ~[na:na]
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081) ~[na:na]
    at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015) ~[na:na]
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(HttpURLConnection.java:1362) ~[na:na]
    at java.base/sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1337) ~[na:na]
    at feign.Client$Default.convertAndSend(Client.java:174) ~[feign-core-10.4.0.jar:na]
    at feign.Client$Default.execute(Client.java:77) ~[feign-core-10.4.0.jar:na]
    at org.springframework.cloud.openfeign.ribbon.FeignLoadBalancer.execute(FeignLoadBalancer.java:93) ~[spring-cloud-openfeign-core-2.2.1.RELEASE.jar:2.2.1.RELEASE]
    at org.springframework.cloud.openfeign.ribbon.FeignLoadBalancer.execute(FeignLoadBalancer.java:56) ~[spring-cloud-openfeign-core-2.2.1.RELEASE.jar:2.2.1.RELEASE]
    at com.netflix.client.AbstractLoadBalancerAwareClient$1.call(AbstractLoadBalancerAwareClient.java:104) ~[ribbon-loadbalancer-2.3.0.jar:2.3.0]
    at com.netflix.loadbalancer.reactive.LoadBalancerCommand$3$1.call(LoadBalancerCommand.java:303) ~[ribbon-loadbalancer-2.3.0.jar:2.3.0]
    at com.netflix.loadbalancer.reactive.LoadBalancerCommand$3$1.call(LoadBalancerCommand.java:287) ~[ribbon-loadbalancer-2.3.0.jar:2.3.0]
    at rx.internal.util.ScalarSynchronousObservable$3.call(ScalarSynchronousObservable.java:231) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.util.ScalarSynchronousObservable$3.call(ScalarSynchronousObservable.java:228) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.Observable.unsafeSubscribe(Observable.java:10327) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeConcatMap$ConcatMapSubscriber.drain(OnSubscribeConcatMap.java:286) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeConcatMap$ConcatMapSubscriber.onNext(OnSubscribeConcatMap.java:144) ~[rxjava-1.3.8.jar:1.3.8]
    at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:185) ~[ribbon-loadbalancer-2.3.0.jar:2.3.0]
    at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:180) ~[ribbon-loadbalancer-2.3.0.jar:2.3.0]
    at rx.Observable.unsafeSubscribe(Observable.java:10327) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:94) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:42) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.Observable.unsafeSubscribe(Observable.java:10327) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber$1.call(OperatorRetryWithPredicate.java:127) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.enqueue(TrampolineScheduler.java:73) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.schedule(TrampolineScheduler.java:52) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:79) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:45) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.util.ScalarSynchronousObservable$WeakSingleProducer.request(ScalarSynchronousObservable.java:276) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.Subscriber.setProducer(Subscriber.java:209) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:138) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:129) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.Observable.subscribe(Observable.java:10423) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.Observable.subscribe(Observable.java:10390) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.observables.BlockingObservable.blockForSingle(BlockingObservable.java:443) ~[rxjava-1.3.8.jar:1.3.8]
    at rx.observables.BlockingObservable.single(BlockingObservable.java:340) ~[rxjava-1.3.8.jar:1.3.8]
    at com.netflix.client.AbstractLoadBalancerAwareClient.executeWithLoadBalancer(AbstractLoadBalancerAwareClient.java:112) ~[ribbon-loadbalancer-2.3.0.jar:2.3.0]
    at org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient.execute(LoadBalancerFeignClient.java:83) ~[spring-cloud-openfeign-core-2.2.1.RELEASE.jar:2.2.1.RELEASE]
    at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:110) ~[feign-core-10.4.0.jar:na]
    at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:80) ~[feign-core-10.4.0.jar:na]
    at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103) ~[feign-core-10.4.0.jar:na]
    at com.sun.proxy.$Proxy104.checkPincodeServiceability(Unknown Source) ~[na:na]
    at com.example.serviceregistrationanddiscoveryclient.ServiceInstanceRestController.serviceInstancesByApplicationName(ServiceRegistrationAndDiscoveryClientApplication.java:46) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.30.jar:9.0.30]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.3.RELEASE.jar:5.2.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.30.jar:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.30.jar:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.30.jar:9.0.30]

编辑1:
下面是我的 application.properties

spring.application.name=test-client
eureka.client.serviceUrl.defaultZone=http://eurekahost:8761/eureka/

Answer 1

最近我也遇到了同样的问题。在使用 localhost 时，我有点能够找出这种行为的根本原因。
Screenshot of issue reproduced at local
发生这种情况的全部原因是 Eureka 服务器无法解决
http://currency-exchange-service/currency-exchange/from/USD/to/INR
到 http://localhost:9093/currency-exchange/from/USD/to/INR
如果您检查您的 Eureka 服务器仪表板并将鼠标悬停在注册的服务上，您将看到 eureka 服务器指向的主机名，如下面的屏幕截图所示。如果您悬停链接(在状态列下)，我们看到的主机名不正确，这会导致此问题。
Screenshot of Eureka dashboard, the cause of the issue
解决方案:
在 Eureka 客户端应用程序的 application.properties 文件中添加以下属性
eureka.instance.hostname=localhost
在您的情况下，请输入适当的主机名。
应该就是这样。进行更改后重新启动您的客户端应用程序。
Go to you Eureka Dashboard 再次悬停注册应用程序的链接，这应该如下所示:
Screen shot of Eureka server dashboard after making the appropriate changes .
进行更改后，请尝试使用 feign 客户端访问您的 Http 请求。它对我有用。
Screenshot of the final result with API result