Error while running the docker image | JNI error

I am getting an error while running a docker image. I have created a core java application using gradle.

using docker build command to create the docker image and while running the docker image I am getting the following error

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/kafka/clients/consumer/Consumer
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
        at java.lang.Class.privateGetMethodRecursive(Class.java:3048)
        at java.lang.Class.getMethod0(Class.java:3018)
        at java.lang.Class.getMethod(Class.java:1784)
        at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:650)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:632)
Caused by: java.lang.ClassNotFoundException: org.apache.kafka.clients.consumer.Consumer
        at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
        ... 7 more

I can see that the error is due to missing kafka consumer library, but I am not able to understand what I have missed in the docker file which is causing this issue.

Here is the dockerfile

FROM openjdk:8
ADD build/libs/*.jar parallel.jar

RUN bash -c 'touch /parallel.jar'
ENTRYPOINT ["java", "-jar", "parallel.jar"]

Before I ran the docker build command, I made sure to run the gradle clean build command.

Here are the dependencies I have used in build.gradle

    implementation "io.confluent.parallelconsumer:parallel-consumer-core:0.5.2.4"
    implementation "org.apache.avro:avro:1.11.1"
    implementation "io.confluent:kafka-avro-serializer:3.3.0"
    implementation "org.springframework.boot:spring-boot-starter-web"
    implementation "org.codehaus.jackson:jackson-core-asl:1.9.13"
    implementation "org.codehaus.jackson:jackson-mapper-asl:1.9.13"
    implementation "org.apache.commons:commons-lang3:3.12.0"
    implementation "org.slf4j:slf4j-simple:2.0.0"
    implementation "me.tongfei:progressbar:0.9.3"
    implementation 'org.awaitility:awaitility:4.2.0'
    implementation("log4j:log4j:1.2.17")

Gradle doesn't include dependencies, by default. You'd get the same error when running java jar outside of the container.

You need to use shadow plugin to get dependencies packaged in your JAR.

Alternatively, don't write a Dockerfile manually... Use jib-gradle-plugin. Plus, it'll create a more optimized Docker image, which doesn't create an Uber JAR like the shadow plugin would.