java.lang.ClassNotFoundException: io.fabric8.kubernetes.client.DefaultKubernetesClient

[iampratapak]

Describe the bug

I'm using io.fabric8:kubernetes-client:6.1.1 and am running a simple client creation code:

final var kubernetesClient = new KubernetesClientBuilder().build();
System.out.println(kubernetesClient.getNamespace());

module-info.java

module com.some.module {
    requires kubernetes.client.api;
}

Error:

java.lang.ClassNotFoundException: io.fabric8.kubernetes.client.DefaultKubernetesClient

In module-info.java, if I use kubernetes.client instead of kubernetes.client.api, then I'mgetting the below error

module com.some.module {
    requires kubernetes.client;
}

java: module xyz reads package io.fabric8.kubernetes.client from both kubernetes.client.api and kubernetes.client

Since DefaultKubernetesClient is deprecated in 6.1.1, I'm using KubernetesClientBuilder.

Fabric8 Kubernetes Client version

6.1.1

Steps to reproduce

1. Use io.fabric8:kubernetes-client:6.1.1
2. In module-info.java add requires kubernetes.client.api

module com.some.module {
    requires kubernetes.client.api;
}

3. Try to create a Kubernetes client using KubernetesClientBuilder

import io.fabric8.kubernetes.client.KubernetesClientBuilder;

public class Example {
    public static void main(String[] args) {
        final var kubernetesClient = new KubernetesClientBuilder().build();
        System.out.println(kubernetesClient.getNamespace());

    }
}

Expected behavior

Kubernetes client should be created without any errors

Runtime

other (please specify in additional context)

Kubernetes API Server version

other (please specify in additional context)

Environment

Windows

Fabric8 Kubernetes Client Logs

Exception in thread "main" io.fabric8.kubernetes.client.KubernetesClientException: An error has occurred.
	at kubernetes.client.api@6.1.1/io.fabric8.kubernetes.client.KubernetesClientException.launderThrowable(KubernetesClientException.java:129)
	at kubernetes.client.api@6.1.1/io.fabric8.kubernetes.client.KubernetesClientException.launderThrowable(KubernetesClientException.java:122)
	at kubernetes.client.api@6.1.1/io.fabric8.kubernetes.client.KubernetesClientBuilder.<init>(KubernetesClientBuilder.java:58)
	at com.some.module/com.some.module.Main.main(Main.java:106)
Caused by: java.lang.ClassNotFoundException: io.fabric8.kubernetes.client.DefaultKubernetesClient
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
	at kubernetes.client.api@6.1.1/io.fabric8.kubernetes.client.KubernetesClientBuilder.<init>(KubernetesClientBuilder.java:56)
	... 1 more

Additional context

Client Version: version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.0", GitCommit:"cb303e613a121a29364f75cc67d3d580833a7479", GitTreeState:"clean", BuildDate:"2021-04-08T16:31:21Z", GoVersion:"go1.16.1", Compiler:"gc", Platform:"windows/amd64"}
Server Version: version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.1", GitCommit:"5e58841cce77d4bc13713ad2b91fa0d961e69192", GitTreeState:"clean", BuildDate:"2021-05-12T14:12:29Z", GoVersion:"go1.16.4", Compiler:"gc", Platform:"linux/amd64"}

<dependency>
      <groupId>io.fabric8</groupId>
      <artifactId>knative-client</artifactId>
      <version>6.1.1</version>
</dependency>

[shawkins]

I don't think the kubernetes client will currently work with Java modules due to the split packages. Can you see if #4464 will work for your usage?

[iampratapak]

Thanks for the quick response, @shawkins. #4464 may work for my use case. I'll wait for the next release.

[manusa]

Hi @pratapgowda007
Once we merge the PR it would be great if you could confirm if the 6.2-SNAPSHOT nightly build resolves your issue.

[iampratapak]

@manusa Sure, please let me know once it's merged

[iampratapak]

@manusa
I just cloned PR #4460 and tested. I can confirm 6.2-SNAPSHOT resolves my issue.

[iampratapak]

@rohanKanojia May I know the tentative release date for 6.2.x?

[rohanKanojia]

I think we should be releasing in upcoming sprint. So within 2-3 weeks from now if everything goes as expected.

[iampratapak]

I think we should be releasing in upcoming sprint. So within 2-3 weeks from now if everything goes as expected.

Thank you

[mayankkulshreshtha]

java.lang.NoClassDefFoundError: io/fabric8/kubernetes/model/jackson/UnmatchedFieldTypeModule
at io.fabric8.kubernetes.client.utils.KubernetesSerialization.(KubernetesSerialization.java:68) ~[kubernetes-client-api-6.10.0.jar:?]
at io.fabric8.kubernetes.client.utils.KubernetesSerialization.(KubernetesSerialization.java:76) ~[kubernetes-client-api-6.10.0.jar:?]
at io.fabric8.kubernetes.client.KubernetesClientBuilder.(KubernetesClientBuilder.java:51) ~[kubernetes-client-api-6.10.0.jar:?]

[manusa]

java.lang.NoClassDefFoundError: io/fabric8/kubernetes/model/jackson/UnmatchedFieldTypeModule at io.fabric8.kubernetes.client.utils.KubernetesSerialization.(KubernetesSerialization.java:68) ~[kubernetes-client-api-6.10.0.jar:?] at io.fabric8.kubernetes.client.utils.KubernetesSerialization.(KubernetesSerialization.java:76) ~[kubernetes-client-api-6.10.0.jar:?] at io.fabric8.kubernetes.client.KubernetesClientBuilder.(KubernetesClientBuilder.java:51) ~[kubernetes-client-api-6.10.0.jar:?]

Hi @mayankkulshreshtha

Make sure yuo don't have convergence issues with Spring Cloud or any other dependency that may bring in their own Kubernetes Client Version.

https://github.com/fabric8io/kubernetes-client/blob/main/doc/FAQ.md#ive-tried-adding-a-dependency-to-kubernetes-client-but-im-still-getting-weird-class-loading-issues-what-gives