Spring Connection prematurely closed BEFORE response when using Spring WebClient with Wiremock proxy

When getting a URL using Spring WebClient with ReactorClientHttpConnector, and using Wiremock as a proxy, it fails with Connection prematurely closed BEFORE response, see stack trace below.

The same setup works fine with other HTTP client libraries, at least with okhttp3.

Hopefully the example code included should be easy enough to understand. Wiremock is set up to enable proxying, all requests are set to return the string "foo" as text/plain.

When making a request with WebClient, the result is expected to be "foo", but it instead fails with the stack stack trace as shown below.

See example at the end, and also a runnable test in the Git repository here: https://github.com/vetler/spring-webclient-bug

This works fine with JettyClientHttpConnector, branch with passing test for that here: https://github.com/vetler/spring-webclient-bug/tree/test/jettyclienthttpconnector

org.springframework.web.reactive.function.client.WebClientRequestException: Connection prematurely closed BEFORE response; nested exception is reactor.netty.http.client.PrematureCloseException: Connection prematurely closed BEFORE response

    at org.springframework.web.reactive.function.client.ExchangeFunctions$DefaultExchangeFunction.lambda$wrapException$9(ExchangeFunctions.java:141)
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ⇢ Request to GET http://example.com [DefaultWebClient]
Stack trace:
        at org.springframework.web.reactive.function.client.ExchangeFunctions$DefaultExchangeFunction.lambda$wrapException$9(ExchangeFunctions.java:141)
        at reactor.core.publisher.MonoErrorSupplied.subscribe(MonoErrorSupplied.java:55)
        at reactor.core.publisher.Mono.subscribe(Mono.java:4361)
        at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103)
        at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:222)
        at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:222)
        at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:222)
        at reactor.core.publisher.MonoNext$NextSubscriber.onError(MonoNext.java:93)
        at reactor.core.publisher.MonoFlatMapMany$FlatMapManyMain.onError(MonoFlatMapMany.java:204)
        at reactor.core.publisher.SerializedSubscriber.onError(SerializedSubscriber.java:124)
        at reactor.core.publisher.FluxRetryWhen$RetryWhenMainSubscriber.whenError(FluxRetryWhen.java:225)
        at reactor.core.publisher.FluxRetryWhen$RetryWhenOtherSubscriber.onError(FluxRetryWhen.java:274)
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:414)
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onNext(FluxConcatMap.java:251)
        at reactor.core.publisher.EmitterProcessor.drain(EmitterProcessor.java:491)
        at reactor.core.publisher.EmitterProcessor.tryEmitNext(EmitterProcessor.java:299)
        at reactor.core.publisher.SinkManySerialized.tryEmitNext(SinkManySerialized.java:100)
        at reactor.core.publisher.InternalManySink.emitNext(InternalManySink.java:27)
        at reactor.core.publisher.FluxRetryWhen$RetryWhenMainSubscriber.onError(FluxRetryWhen.java:190)
        at reactor.core.publisher.MonoCreate$DefaultMonoSink.error(MonoCreate.java:189)
        at reactor.netty.http.client.HttpClientConnect$HttpObserver.onUncaughtException(HttpClientConnect.java:384)
        at reactor.netty.ReactorNetty$CompositeConnectionObserver.onUncaughtException(ReactorNetty.java:647)
        at reactor.netty.resources.DefaultPooledConnectionProvider$DisposableAcquire.onUncaughtException(DefaultPooledConnectionProvider.java:219)
        at reactor.netty.resources.DefaultPooledConnectionProvider$PooledConnection.onUncaughtException(DefaultPooledConnectionProvider.java:467)
        at reactor.netty.http.client.HttpClientOperations.onInboundClose(HttpClientOperations.java:289)
        at reactor.netty.channel.ChannelOperationsHandler.channelInactive(ChannelOperationsHandler.java:73)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:262)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:248)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:241)
        at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelInactive(CombinedChannelDuplexHandler.java:418)
        at io.netty.handler.codec.ByteToMessageDecoder.channelInputClosed(ByteToMessageDecoder.java:389)
        at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:354)
        at io.netty.handler.codec.http.HttpClientCodec$Decoder.channelInactive(HttpClientCodec.java:326)
        at io.netty.channel.CombinedChannelDuplexHandler.channelInactive(CombinedChannelDuplexHandler.java:221)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:262)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:248)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:241)
        at io.netty.handler.proxy.ProxyHandler.channelInactive(ProxyHandler.java:230)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:262)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:248)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:241)
        at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelInactive(CombinedChannelDuplexHandler.java:418)
        at io.netty.channel.CombinedChannelDuplexHandler.channelInactive(CombinedChannelDuplexHandler.java:223)
        at io.netty.handler.proxy.HttpProxyHandler$HttpClientCodecWrapper.channelInactive(HttpProxyHandler.java:267)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:262)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:248)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:241)
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelInactive(DefaultChannelPipeline.java:1405)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:262)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:248)
        at io.netty.channel.DefaultChannelPipeline.fireChannelInactive(DefaultChannelPipeline.java:901)
        at io.netty.channel.AbstractChannel$AbstractUnsafe$8.run(AbstractChannel.java:831)
        at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:164)
        at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java)
        at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:469)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:497)
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:986)
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
        at java.base/java.lang.Thread.run(Thread.java:829)
    Suppressed: java.lang.Exception: #block terminated with an error
        at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:99)
        at reactor.core.publisher.Mono.block(Mono.java:1706)
        at com.example.demo.DemoApplicationTests.contextLoads(DemoApplicationTests.java:37)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
        at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
        at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
        at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
        at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
        at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
        at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
        at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
        at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
        at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
        at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
        at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
        at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
        at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
        at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:210)
        at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
        at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:206)
        at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:131)
        at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
        at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
        at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
        at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
        at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
        at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
        at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
        at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
        at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
        at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
        at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
        at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
        at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
        at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
        at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
        at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
        at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
        at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
        at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
        at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
        at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
        at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
        at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
        at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
        at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
        at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
        at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
        at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
        at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: reactor.netty.http.client.PrematureCloseException: Connection prematurely closed BEFORE response

Disconnected from the target VM, address: '127.0.0.1:54721', transport: 'socket'

Process finished with exit code -1

Here is a test to reproduce:

@SpringBootTest
class DemoApplicationTests {
    @RegisterExtension
    WireMockExtension wm1 = WireMockExtension.newInstance()
            .options(wireMockConfig().enableBrowserProxying(true).port(10001))
            .build();

    @Test
    void contextLoads() {
        wm1.stubFor(
                get(urlMatching(".*"))
                        .willReturn(
                                aResponse()
                                        .withHeader("Content-Type", "text/plain")
                                        .withBody("foo")
                        )
        );

        System.setProperty("http.proxyHost", "localhost");
        System.setProperty("http.proxyPort", Integer.toString(wm1.getRuntimeInfo().getHttpPort()));

        WebClient client = WebClient.builder().clientConnector(new ReactorClientHttpConnector(HttpClient.create().proxyWithSystemProperties())).build();
        String result = client.get().uri("http://example.com").retrieve().bodyToMono(String.class).block();

        assertEquals("foo", result);
    }

}

Comment From: rafamdr

Hello @vetler,

I believe I'm facing a similar problem when I'm using MockWebServer to test a WebClient. The connection is being closed before receiving response from MockWebServer (with same reason).

Those repositories you shared are inaccessible (at least for me). Are they set as private?

Comment From: vetler

Whoops, yes the repository was private. Should be public now, @rafamdr

Comment From: rafamdr

I've just tested and JettyClientHttpConnector also worked for my case.

Comment From: ulischulte

This was also reported in Spring-Boot-Admin (for instance https://github.com/codecentric/spring-boot-admin/issues/1711 ) by multiple users. It may not be connected to wiremock specifically since wiremock was not involved in those issues.

Comment From: rstoyanchev

Have you tried this with Reactor Netty HttpClient directly? It might be unrelated to the WebClient if it works with other connectors.

Comment From: vetler

That's a great point, will try to find the time to create a test case for that as well.

Comment From: vetler

Reactor Netty HttpClient test case created and reported in Reactor Netty here: https://github.com/reactor/reactor-netty/issues/1857