I am building a shaded jar that I want to run on a Kafka Connect cluster. This jar is a simple gRPC client that consumes Kafka messages from a topic then sends them to a server. However, when I run my jar on the Kafka Connect cluster it gives me this error:

java.util.ServiceConfigurationError: io.grpc.ManagedChannelProvider: io.grpc.netty.NettyChannelProvider not a subtype
     at java.base/java.util.ServiceLoader.fail(ServiceLoader.java:593)
     at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.hasNextService(ServiceLoader.java:1244)
     at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.hasNext(ServiceLoader.java:1273)
     at java.base/java.util.ServiceLoader$2.hasNext(ServiceLoader.java:1309)
     at java.base/java.util.ServiceLoader$3.hasNext(ServiceLoader.java:1393)
     at io.grpc.ServiceProviders.loadAll(ServiceProviders.java:67)
     at io.grpc.ManagedChannelRegistry.getDefaultRegistry(ManagedChannelRegistry.java:101)
     at io.grpc.ManagedChannelProvider.provider(ManagedChannelProvider.java:43)
     at io.grpc.ManagedChannelBuilder.forAddress(ManagedChannelBuilder.java:44)
     at com.pinax.kafka.paymentgateway.connect.sink.PaymentGatewayClient.start(PaymentGatewayClient.java:46)
     at com.pinax.kafka.paymentgateway.connect.sink.PaymentGatewaySinkTask.start(PaymentGatewaySinkTask.java:29)
     at org.apache.kafka.connect.runtime.WorkerSinkTask.initializeAndStart(WorkerSinkTask.java:333)
     at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:227)
     at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:284)
     at org.apache.kafka.connect.runtime.isolation.Plugins.lambda$withClassLoader$7(Plugins.java:339)
     at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
     at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
     at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)

I really dont understand what is the issue here. It seems that grpc-netty-shaded cannot find the type that should normally be there. Here’s what I’m doing in my pom.xml:

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.pinax.kafka.paymentgateway.connect.sink</groupId>
  <artifactId>pinax-payment-gateway-kafka-connect</artifactId>
  <version>0.0.1</version>

  <name>pinax-payment-gateway-kafka-connect</name>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
    <grpc.version>1.66.0</grpc.version>
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-bom</artifactId>
        <version>${grpc.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>

    <!--Kafka Connect dependencies-->
    <dependency>
      <groupId>org.apache.kafka</groupId>
      <artifactId>connect-api</artifactId>
      <version>3.7.0</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
        <groupId>com.google.protobuf</groupId>
        <artifactId>protobuf-java-util</artifactId>
        <version>4.28.0</version>
    </dependency>

    <!--gRPC dependencies-->
    <dependency>
      <groupId>io.grpc</groupId>
      <artifactId>grpc-netty-shaded</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>io.grpc</groupId>
      <artifactId>grpc-stub</artifactId>
    </dependency>
    <dependency>
      <groupId>io.grpc</groupId>
      <artifactId>grpc-protobuf</artifactId>
    </dependency>

    <!--For proto annotation-->
    <dependency>
      <groupId>org.apache.tomcat</groupId>
      <artifactId>annotations-api</artifactId>
      <version>6.0.53</version>
      <scope>provided</scope>
    </dependency>

  </dependencies>

  <build>

      <extensions>
        <extension>
          <groupId>kr.motd.maven</groupId>
          <artifactId>os-maven-plugin</artifactId>
          <version>1.7.1</version>
        </extension>
      </extensions>

      <plugins>

        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-shade-plugin</artifactId>
          <version>3.6.0</version>
          <executions>
            <execution>
              <phase>package</phase>
              <goals>
                <goal>shade</goal>
              </goals>
              <configuration>
                <createDependencyReducedPom>false</createDependencyReducedPom>
                <transformers>
                  <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
                </transformers>
              </configuration>
            </execution>
          </executions>
        </plugin>

        <plugin>
          <groupId>org.xolstice.maven.plugins</groupId>
          <artifactId>protobuf-maven-plugin</artifactId>
          <version>0.6.1</version>
          <configuration>
            <protocArtifact>com.google.protobuf:protoc:3.25.3:exe:${os.detected.classifier}</protocArtifact>
            <pluginId>grpc-java</pluginId>
            <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.66.0:exe:${os.detected.classifier}</pluginArtifact>
            <clearOutputDirectory>false</clearOutputDirectory>
            <outputDirectory>${basedir}/src/main/java</outputDirectory>
          </configuration>
          <executions>
            <execution>
              <goals>
                <goal>compile</goal>
                <goal>compile-custom</goal>
              </goals>
            </execution>
          </executions>
        </plugin>

      </plugins>

  </build>
</project>

So it creates two jars, one being the jar with all dependencies.

Thanks

I’ve been stuck on this issue for a long time now, even tried to use grpc-netty without the shaded but when I decompile the jar it always seem like grpc-netty-shaded is used.