Kubernetes Java API client Example

by Anish

Posted on Tuesday July 30th 2019

In this blog we will learn how to access your kubernetes cluster from your Java Client. For this you need the following Information

• Locate where your cluster-API is running

    root# kubectl cluster-info
    Kubernetes master is running at https://192.0.2.80:6443
    coredns is running at https://192.0.2.80:6443/api/v1/namespaces/kube-system/services/coredns:dns/proxy
    kubernetes-dashboard is running at https://192.0.2.80:6443/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy
  

• Locate the kubeconfig file, This can be found at the below location

     root# cat $HOME/.kube/config
  

• Save this file(config) on your Java project, we will lookup this file(config) using our sample java client program as shown below. This program uses Corev1 API and list all the pod in all the namespace.

  import io.kubernetes.client.ApiClient;
  import io.kubernetes.client.ApiException;
  import io.kubernetes.client.Configuration;
  import io.kubernetes.client.apis.CoreV1Api;
  import io.kubernetes.client.models.V1Pod;
  import io.kubernetes.client.models.V1PodList;
  import io.kubernetes.client.util.Config;
  
  import java.io.IOException;
  
  public class Example {
      public static void main(String[] args) throws IOException, ApiException{
          ApiClient client = Config.fromConfig("config");
          client.setVerifyingSsl(false);
          Configuration.setDefaultApiClient(client);
  
          CoreV1Api api = new CoreV1Api();
          V1PodList list = api.listPodForAllNamespaces(null, null, null, null, null, null, null, null, null);
          for (V1Pod item : list.getItems()) {
              System.out.println(item.getMetadata().getName());
          }
      }
  }
  

• To compile this program add the required dependency for kubernetes java api client in the Pom.xml

  <dependency>
  <groupId>io.kubernetes</groupId>
  <artifactId>client-java</artifactId>
  <version>5.0.0</version>
  <scope>compile</scope>
  </dependency>
  

• Now we have every thing ready to connect and run the program, I have used eclipse to compile and run this Application

Video Demo

Next Reading : How to Monitoring All Executed Commands in Linux

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