How to read data from RabbitMQ using Apache Beam

Question

I have a prototype Apache Beam pipeline where I try to read data from RabbitMQ using the following configuration

        p.apply("read_from_rabbit", RabbitMqIO.read()
                .withUri(options.getRabbitMQUri())
                .withQueue(options.getRabbitMQQueue())
                )
            .apply("extract_json_data", MapElements.via(new RabbitMessageToKafkaMessage()))

when I try to run it, I always get

Exception in thread "main" java.lang.NoClassDefFoundError: com/rabbitmq/client/QueueingConsumer$Delivery
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
    at java.lang.Class.getDeclaredConstructors(Class.java:2020)
    at java.io.ObjectStreamClass.computeDefaultSUID(ObjectStreamClass.java:1793)
    at java.io.ObjectStreamClass.access$100(ObjectStreamClass.java:72)
    at java.io.ObjectStreamClass$1.run(ObjectStreamClass.java:253)
    at java.io.ObjectStreamClass$1.run(ObjectStreamClass.java:251)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.io.ObjectStreamClass.getSerialVersionUID(ObjectStreamClass.java:250)
    at java.io.ObjectStreamClass.writeNonProxy(ObjectStreamClass.java:735)
    at java.io.ObjectOutputStream.writeClassDescriptor(ObjectOutputStream.java:668)
    at java.io.ObjectOutputStream.writeNonProxyDesc(ObjectOutputStream.java:1282)
    at java.io.ObjectOutputStream.writeClassDesc(ObjectOutputStream.java:1231)
    at java.io.ObjectOutputStream.writeClass(ObjectOutputStream.java:1213)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1120)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
    at org.apache.beam.sdk.util.SerializableUtils.serializeToByteArray(SerializableUtils.java:51)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.CoderTranslation.toCustomCoder(CoderTranslation.java:119)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.CoderTranslation.toProto(CoderTranslation.java:83)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.SdkComponents.registerCoder(SdkComponents.java:250)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.PCollectionTranslation.toProto(PCollectionTranslation.java:35)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.SdkComponents.registerPCollection(SdkComponents.java:205)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.PTransformTranslation.translateAppliedPTransform(PTransformTranslation.java:369)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.ParDoTranslation$ParDoTranslator.translate(ParDoTranslation.java:120)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.PTransformTranslation.toProto(PTransformTranslation.java:149)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.ParDoTranslation.getParDoPayload(ParDoTranslation.java:651)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.ParDoTranslation.isSplittable(ParDoTranslation.java:666)
    at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.construction.PTransformMatchers$6.matches(PTransformMatchers.java:269)
    at org.apache.beam.sdk.Pipeline$2.visitPrimitiveTransform(Pipeline.java:280)
    at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:665)
    at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:657)
    at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:657)
    at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:657)
    at org.apache.beam.sdk.runners.TransformHierarchy$Node.access$600(TransformHierarchy.java:317)
    at org.apache.beam.sdk.runners.TransformHierarchy.visit(TransformHierarchy.java:251)
    at org.apache.beam.sdk.Pipeline.traverseTopologically(Pipeline.java:458)
    at org.apache.beam.sdk.Pipeline.replace(Pipeline.java:258)
    at org.apache.beam.sdk.Pipeline.replaceAll(Pipeline.java:208)
    at org.apache.beam.runners.direct.DirectRunner.run(DirectRunner.java:154)
    at org.apache.beam.runners.direct.DirectRunner.run(DirectRunner.java:64)
    at org.apache.beam.sdk.Pipeline.run(Pipeline.java:313)
    at org.apache.beam.sdk.Pipeline.run(Pipeline.java:299)
    at myCompany.myProject.RabbitToKafka.runTransformer(RabbitToKafka.java:54)
    at myCompany.myProject.RabbitToKafka.main(RabbitToKafka.java:61)
Caused by: java.lang.ClassNotFoundException: com.rabbitmq.client.QueueingConsumer$Delivery
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 48 more

My understanding is that since my RabbitMessageToKafkaMessage class read RabbitMQ messages, these messages in turn contain RabbitMQ data, in particular delivery information injected into constructor : public RabbitMqMessage(String routingKey, QueueingConsumer.Delivery delivery) { Is this ok ?

If so, how can I transform my RabbitMQMessage into a KV during the read operation ?

EDIT 1 error happens when running my pipeline from Eclipse.

EDIT 2 That project is a maven project run using Eclipse. My Apache Bean dependencies are all at the 2.12.0 version (which is the latest).

My dependency tree is as follows (at least the part regarding RabbitMQ)

myCompany:myProject:jar:0.1.5-SNAPSHOT
+- org.apache.beam:beam-sdks-java-io-rabbitmq:jar:2.12.0:compile
|  \- com.rabbitmq:amqp-client:jar:5.4.3:compile

Answer 1

As it appear, merging my previous pom with an Apache Beam compatible one was not a good idea, as it created a conflict between two different versions of amqp-client. Removing the Spring boot parent pom solved the bug, by removing the bad amqp-client version.

Answer 2

Looks like there're some rough edges in dependency management. The following steps may help to find the problem:

1. Confirm that the missing class (or the amqp-client jar) is on a runtime class path
2. Build uberjar and try to run it from commandline
3. Try with different runners (FlinkRunner, DataflowRunner)
4. Try with the latest version of Beam