Caused by: java.lang.ClassNotFoundException: io.confluent.monitoring.clients.interceptor.MonitoringProducerInterceptor

问题

Trying to publish message to kafka topic using rest proxy by Confluent platform using this command and responds with an error as mentioned below

Request:

$ curl -X POST -H "Content-Type: application/vnd.kafka.avro.v2+json" \
      -H "Accept: application/vnd.kafka.v2+json" \
      --data '{"value_schema": "{\"type\": \"record\", \"name\": \"User\", \"fields\": [{\"name\": \"name\", \"type\": \"string\"}]}", "records": [{"value": {"name": "test name"}}]}' \
      "http://${RESTPROXY_HOST}:8082/topics/${TOPIC}"

Response:

{"error_code":500,"message":"Internal Server Error"}

Error log from ./kafka-rest/logs/kafka-rest.log

[2018-08-06 14:29:00,734] INFO [Producer clientId=producer-4] Closing the Kafka producer with timeoutMillis = 0 ms. (org.apache.kafka.clients.producer.KafkaProducer)
[2018-08-06 14:29:00,734] ERROR Unhandled exception resulting in internal server error response (io.confluent.rest.exceptions.GenericExceptionMapper)
java.lang.reflect.UndeclaredThrowableException
    at com.sun.proxy.$Proxy12.getProducerPool(Unknown Source)
    at io.confluent.kafkarest.resources.TopicsResource.produce(TopicsResource.java:147)
    at io.confluent.kafkarest.resources.TopicsResource.produceAvro(TopicsResource.java:135)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
    at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$VoidOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:143)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
    at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
    at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
    at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
    at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
    at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
    at org.glassfish.jersey.servlet.ServletContainer.serviceImpl(ServletContainer.java:408)
    at org.glassfish.jersey.servlet.ServletContainer.doFilter(ServletContainer.java:583)
    at org.glassfish.jersey.servlet.ServletContainer.doFilter(ServletContainer.java:524)
    at org.glassfish.jersey.servlet.ServletContainer.doFilter(ServletContainer.java:461)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:221)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:110)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
    at org.eclipse.jetty.server.handler.StatisticsHandler.handle(StatisticsHandler.java:159)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
    at org.eclipse.jetty.server.Server.handle(Server.java:499)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:258)
    at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:544)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at io.confluent.kafkarest.extension.ContextInvocationHandler.invoke(ContextInvocationHandler.java:33)
    ... 48 more
Caused by: org.apache.kafka.common.KafkaException: Failed to construct kafka producer
    at org.apache.kafka.clients.producer.KafkaProducer.<init>(KafkaProducer.java:459)
    at org.apache.kafka.clients.producer.KafkaProducer.<init>(KafkaProducer.java:289)
    at io.confluent.kafkarest.ProducerPool.buildNoSchemaProducer(ProducerPool.java:109)
    at io.confluent.kafkarest.ProducerPool.buildBinaryProducer(ProducerPool.java:95)
    at io.confluent.kafkarest.ProducerPool.<init>(ProducerPool.java:68)
    at io.confluent.kafkarest.ProducerPool.<init>(ProducerPool.java:57)
    at io.confluent.kafkarest.ProducerPool.<init>(ProducerPool.java:50)
    at io.confluent.kafkarest.DefaultKafkaRestContext.getProducerPool(DefaultKafkaRestContext.java:70)
    ... 53 more
Caused by: org.apache.kafka.common.KafkaException: io.confluent.monitoring.clients.interceptor.MonitoringProducerInterceptor ClassNotFoundException exception occurred
    at org.apache.kafka.common.config.AbstractConfig.getConfiguredInstances(AbstractConfig.java:357)
    at org.apache.kafka.common.config.AbstractConfig.getConfiguredInstances(AbstractConfig.java:332)
    at org.apache.kafka.common.config.AbstractConfig.getConfiguredInstances(AbstractConfig.java:319)
    at org.apache.kafka.clients.producer.KafkaProducer.<init>(KafkaProducer.java:380)
    ... 60 more
Caused by: java.lang.ClassNotFoundException: io.confluent.monitoring.clients.interceptor.MonitoringProducerInterceptor
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at org.apache.kafka.common.utils.Utils.loadClass(Utils.java:322)
    at org.apache.kafka.common.utils.Utils.newInstance(Utils.java:311)
    at org.apache.kafka.common.config.AbstractConfig.getConfiguredInstances(AbstractConfig.java:355)
    ... 63 more

回答1:

Short

io.confluent.monitoring.clients.interceptor.MonitoringProducerInterceptor class does not exists in Kafka rest proxy class path.

placing monitoring-interceptors.jar in Kafka rest proxy(or which ever confluent service failing due to this error) classpath should solve the issue

---

Detail

This jar can found at local $CONFLUENT_HOME/share/java/monitoring-interceptors/monitoring-interceptors-*.jar

or confluent maven repo with

group: "io.confluent", artifact: "monitoring-interceptors", version: "4.1.0"

$ cd $CONFLUENT_HOME
$ cp ./share/java/monitoring-interceptors/monitoring-interceptors-4.1.0.jar \
   ./share/java/kafka-rest/

$ ./bin/confluent stop kafka-rest
$ ./bin/confluent start kafka-rest

来源：https://stackoverflow.com/questions/51702911/caused-by-java-lang-classnotfoundexception-io-confluent-monitoring-clients-int