Can't run embedded server with kafka-avro-serializer dep

Hello, I’m trying to write tests for my producer however I’m not having any luck. I am simply calling EmbeddedKafka.start() but this fails immediately with the exception below:

Exception Stack

A needed class was not found. This could be due to an error in your runpath. Missing class: org/apache/kafka/common/metrics/MetricsContext
java.lang.NoClassDefFoundError: org/apache/kafka/common/metrics/MetricsContext
	at net.manub.embeddedkafka.ops.KafkaOps.startKafka(kafkaOps.scala:52)
	at net.manub.embeddedkafka.ops.KafkaOps.startKafka$(kafkaOps.scala:26)
	at net.manub.embeddedkafka.EmbeddedKafka$.startKafka(EmbeddedKafka.scala:52)
	at net.manub.embeddedkafka.ops.RunningKafkaOps.startKafka(kafkaOps.scala:81)
	at net.manub.embeddedkafka.ops.RunningKafkaOps.startKafka$(kafkaOps.scala:74)
	at net.manub.embeddedkafka.EmbeddedKafka$.startKafka(EmbeddedKafka.scala:52)
	at net.manub.embeddedkafka.EmbeddedKafka$.start(EmbeddedKafka.scala:70)
	at whoseturn.test.support.kafka.KafkaSupport.beforeAll(KafkaSupport.scala:10)
	at whoseturn.test.support.kafka.KafkaSupport.beforeAll$(KafkaSupport.scala:9)
	at whoseturn.web.todos.TodoFeedItemProducerSpec.beforeAll(TodoFeedItemProducerSpec.scala:14)
	at org.scalatest.BeforeAndAfterAll.liftedTree1$1(BeforeAndAfterAll.scala:212)
	at org.scalatest.BeforeAndAfterAll.run(BeforeAndAfterAll.scala:210)
	at org.scalatest.BeforeAndAfterAll.run$(BeforeAndAfterAll.scala:208)
	at whoseturn.web.todos.TodoFeedItemProducerSpec.run(TodoFeedItemProducerSpec.scala:14)
	at org.scalatest.tools.SuiteRunner.run(SuiteRunner.scala:45)
	at org.scalatest.tools.Runner$.$anonfun$doRunRunRunDaDoRunRun$13(Runner.scala:1320)
	at org.scalatest.tools.Runner$.$anonfun$doRunRunRunDaDoRunRun$13$adapted(Runner.scala:1314)
	at scala.collection.immutable.List.foreach(List.scala:392)
	at org.scalatest.tools.Runner$.doRunRunRunDaDoRunRun(Runner.scala:1314)
	at org.scalatest.tools.Runner$.$anonfun$runOptionallyWithPassFailReporter$24(Runner.scala:993)
	at org.scalatest.tools.Runner$.$anonfun$runOptionallyWithPassFailReporter$24$adapted(Runner.scala:971)
	at org.scalatest.tools.Runner$.withClassLoaderAndDispatchReporter(Runner.scala:1480)
	at org.scalatest.tools.Runner$.runOptionallyWithPassFailReporter(Runner.scala:971)
	at org.scalatest.tools.Runner$.run(Runner.scala:798)
	at org.scalatest.tools.Runner.run(Runner.scala)
	at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.runScalaTest2or3(ScalaTestRunner.java:40)
	at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.main(ScalaTestRunner.java:27)
Caused by: java.lang.ClassNotFoundException: org.apache.kafka.common.metrics.MetricsContext
	at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	... 27 more

After some time googling, it seems like a dependancy problem so I removed my dependancies one at a time till I stopped getting this error. It turns out if I have kafka-avro-serializeras a dependancy I will get this error. I don’t really understand why and don’t know what a possible solution could be. Any suggestions as to what I can do, I would really like to use both libraries if possible. Below is my build.sbt dependancies.

build.sbt

version := "0.1"

scalaVersion := "2.13.3"
resolvers += "Confluent" at "https://packages.confluent.io/maven/"
libraryDependencies ++= List(
      "org.typelevel"              %% "cats-core"            % "2.1.1",
      "com.typesafe.akka"          %% "akka-stream"          % "2.6.8",
      "org.typelevel"              %% "cats-effect"          % "2.1.4",
      "com.typesafe.scala-logging" %% "scala-logging"        % "3.9.2",
      "org.slf4j"                  % "slf4j-api"             % "1.7.5",
      "org.slf4j"                  % "slf4j-simple"          % "1.7.5",
      "org.apache.commons"         % "commons-io"            % "1.3.2",
      "org.apache.avro"            % "avro"                  % "1.9.2",
      "org.apache.kafka"           % "kafka-clients"         % "2.6.0",
      "io.github.embeddedkafka"    %% "embedded-kafka"       % "2.6.0",
      "io.confluent"               % "kafka-avro-serializer" % "5.5.1"
)

[phamtrinli]

Hi @kelvinmac @francescopellegrini,

I had the similar issue with kafka-streams-avro-serde. Was able to fix this by excluding the kafka-client from kafka-avro-serializer. libraryDependencies += "io.confluent" % "kafka-streams-avro-serde" % "5.5.1" exclude("org.apache.kafka", "kafka-clients") Maybe this is a workaround.

[francescopellegrini]

Hi @kelvinmac, I see that you’re using kafka-avro-serializer v5.5.1 along with embedded-kafka v2.6.0: maybe v2.5.1 would be more appropriate, but anyway I was wondering if you are using Confluent Schema Registry to store Avro schemas, in which case I’d recommend using embedded-kafka-schema-registry v5.5.1. BTW this error is similar to #202, maybe they have something in common…