Wiremock stubFor returns SocketException: Connection reset

Question

I need to mock feign client and I tried to use Wiremock as exemplified at How to write integration tests with spring-cloud-netflix and feign

However I got the following error when calling stubFor

java.net.SocketException: Connection reset

    at java.base/java.net.SocketInputStream.read(SocketInputStream.java:210)
    at java.base/java.net.SocketInputStream.read(SocketInputStream.java:141)
    at org.apache.http.impl.io.SessionInputBufferImpl.streamRead(SessionInputBufferImpl.java:137)
    at org.apache.http.impl.io.SessionInputBufferImpl.fillBuffer(SessionInputBufferImpl.java:153)
    at org.apache.http.impl.io.SessionInputBufferImpl.readLine(SessionInputBufferImpl.java:282)
    at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:138)
    at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:56)
    at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:259)
    at org.apache.http.impl.DefaultBHttpClientConnection.receiveResponseHeader(DefaultBHttpClientConnection.java:163)
    at org.apache.http.impl.conn.CPoolProxy.receiveResponseHeader(CPoolProxy.java:165)
    at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:273)
    at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:125)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:272)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108)
    at com.github.tomakehurst.wiremock.client.HttpAdminClient.safelyExecuteRequest(HttpAdminClient.java:473)
    at com.github.tomakehurst.wiremock.client.HttpAdminClient.executeRequest(HttpAdminClient.java:454)
    at com.github.tomakehurst.wiremock.client.HttpAdminClient.addStubMapping(HttpAdminClient.java:131)
    at com.github.tomakehurst.wiremock.client.WireMock.register(WireMock.java:298)
    at com.github.tomakehurst.wiremock.client.WireMock.register(WireMock.java:293)
    at com.github.tomakehurst.wiremock.client.WireMock.givenThat(WireMock.java:104)
    at com.github.tomakehurst.wiremock.client.WireMock.stubFor(WireMock.java:108)
    at com.example.app.controller.MyIntegrityTest.whenFlagSuccess_thenShouldReturnAllPayments(MyIntegrityTest.java:325)
    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:564)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:73)
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:83)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at com.github.tomakehurst.wiremock.junit.WireMockClassRule$1.evaluate(WireMockClassRule.java:60)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at com.github.tomakehurst.wiremock.junit.WireMockClassRule$1.evaluate(WireMockClassRule.java:70)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

and here is the code of MyIntegrationTest.java

@RunWith(SpringRunner.class)
@SpringBootTest(
        classes = {MyAppTests.class, com.example.app.ContextConfiguration.class},
        properties = {"feign.hystrix.enabled=true"}
)
@EnableAutoConfiguration
@ContextConfiguration(classes = {MyIntegrityTest.LocalRibbonClientConfiguration.class})
public class MyIntegrityTest {

    @ClassRule
    public static WireMockClassRule wiremock = new WireMockClassRule(
            wireMockConfig().dynamicPort());
    @Rule public WireMockClassRule instanceRule = wiremock;

    @TestConfiguration
        public static class LocalRibbonClientConfiguration {

        @Bean
        public ServerList<Server> ribbonServerList() {
            System.out.println("wiremock.port()" + wiremock.port());
            return new StaticServerList<>(new Server("localhost", wiremock.port()));
        }
    }

    @Test
    public void testOne() {
       stubFor(WireMock.post(anyUrl())
                .willReturn(aResponse()
                        .withStatus(HttpStatus.OK.value())
                        .withHeader("Content-Type", javax.ws.rs.core.MediaType.APPLICATION_JSON)
                        .withBody("{}")
                )
        );
    }
}

How to fix it?

Answer 1

If the stubfor method results in a Connection reset, it means that something is listening on your host on that specific port already. You can see that during stubbing it uses an HttpAdminClient to check that port and fires a request towards it. That pre-flight request results in that Connection reset.