Describe the bug Getting Unknown Host exception while using RestClient with Eureka Server. The same code works fine while using RestTemplate but if I switch API call to RestClient, it gives UnknownHostException.
Sample There is a normal API with service name PRODUCER-SERVICE which send basic greeting against a GET endpoint. I tried to call this PRODUCER-SERVICE from another service using a RestClient and Eureka server which is giving exception. If I use LoadBalanced RestTemplate the routing happens fine via EurekaServer but it doesn't work with RestClient call.
Configuration
@Configuration
class ConsumerConfiguration {
@Bean
@LoadBalanced
public RestClient restClient(RestTemplate restTemplate) {
return RestClient.create(restTemplate);
}
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
Controller
@RestController
public class ConsumerServiceController {
@Autowired
RestClient restClient;
@Autowired
RestTemplate restTemplate;
@GetMapping("getGreeting/{userName}")
public String getGreeting(@PathVariable("userName") String userName) {
// Not Working
return restClient.get().uri("http://PRODUCER-SERVICE/producer/getGreeting/{userName}", userName)
.retrieve().body(String.class);
// Working
return restTemplate.getForEntity("http://PRODUCER-SERVICE/producer/getGreeting/{userName}",
String.class, userName);
}
}
Error Log Trace
2023-11-23T01:17:25.749+05:30 ERROR 1760 --- [CONSUMER-SERVICE] [nio-8081-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://PRODUCER-SERVICE/producer/getGreeting/Niket": PRODUCER-SERVICE] with root cause
java.net.UnknownHostException: PRODUCER-SERVICE
at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:567) ~[na:na]
at java.base/java.net.Socket.connect(Socket.java:633) ~[na:na]
at java.base/java.net.Socket.connect(Socket.java:583) ~[na:na]
at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:183) ~[na:na]
at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:534) ~[na:na]
at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:639) ~[na:na]
at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:282) ~[na:na]
at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:387) ~[na:na]
at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:409) ~[na:na]
at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1309) ~[na:na]
at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1242) ~[na:na]
at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1128) ~[na:na]
at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1057) ~[na:na]
at org.springframework.http.client.SimpleClientHttpRequest.executeInternal(SimpleClientHttpRequest.java:79) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.http.client.AbstractStreamingClientHttpRequest.executeInternal(AbstractStreamingClientHttpRequest.java:70) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:66) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.client.DefaultRestClient$DefaultRequestBodyUriSpec.exchangeInternal(DefaultRestClient.java:409) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.client.DefaultRestClient$DefaultRequestBodyUriSpec.retrieve(DefaultRestClient.java:380) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at com.medium.agrawalniket.consumer.controller.ConsumerServiceController.getGreeting(ConsumerServiceController.java:29) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[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:568) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:253) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:181) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:118) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:918) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:830) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1089) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1011) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:527) ~[jakarta.servlet-api-6.0.0.jar:6.0.0]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.1.0-RC1.jar:6.1.0-RC1]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:614) ~[jakarta.servlet-api-6.0.0.jar:6.0.0]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:205) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) ~[tomcat-embed-websocket-10.1.15.jar:10.1.15]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.springframework.web.filter.ServerHttpObservationFilter.doFilterInternal(ServerHttpObservationFilter.java:109) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.1.0-RC1.jar:6.1.0-RC1]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:174) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:149) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:482) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:115) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:340) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:391) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:896) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1744) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-10.1.15.jar:10.1.15]
at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
Comment From: OlgaMaciaszek
Hello @niket17590, as you can see in the docs, for RestClient
, the @LoadBalanced
-annotated bean you need to create is RestClient.Builder
.