K
Q

How to connect to an existing kubernetes server and list all pods using java?

1/9/2019

I'm trying to connect to an existing kubernetes that's running on AWS and run arbitrary commands on it using Java. Specifically, we are using fabric8 (although I am open to another api if you can provide a sufficient answer using one). The reason I need to do this in Java is because we plan to eventually incorporate this into our existing junit live tests.

For now I just need an example of how to connect to the sever and get all of the pod names as an array of Strings. Can somebody show me a simple, concise example of how to do this.

i.e. I want the equivalent of this bash script using a java api (again preferably using fabric8, but I'll accept another api if you know one)

#!bin/bash
kops export kubecfg --name $CLUSTER --state=s3://$STATESTORE

kubectl get pod -o=custom-colums=NAME:.metadata.name -n=$NAMESPACE
-- Alex Parker
amazon-web-services
fabric8
java
kubernetes

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2 Answers

1/10/2019

Here is the fabric8 kubernetes client for kubernetes:

https://github.com/fabric8io/kubernetes-client/

It comes with a fluent DSL to work with kubernetes/Openshift resources. It has got pagination support too. If you want to list resources in certain namespace then you can use inNamespace("your namespace") parameter in dsl.

String master = "https://192.168.42.20:8443/";

Config config = new ConfigBuilder().withMasterUrl(master).build();
try (final KubernetesClient client = new DefaultKubernetesClient(config)) {
  // Simple Listing:
  PodList simplePodList = client.pods().inAnyNamespace().list();      

  // List with limit and continue options:
  PodList podList = client.pods().inAnyNamespace().list(5, null);
  podList.getItems().forEach((obj) -> { System.out.println(obj.getMetadata().getName()); });

  podList = client.pods().inAnyNamespace().list(5, podList.getMetadata().getContinue());
  podList.getItems().forEach((obj) -> { System.out.println(obj.getMetadata().getName()); });

} catch (KubernetesClientException e) {
  logger.error(e.getMessage(), e);
}
-- Rohan Kumar
Source: StackOverflow
1/10/2019

Here is the official Java client for Kubernetes.

https://github.com/kubernetes-client/java

It gives you a clean interface and write code in java to execute against kubernetes.

As listed in the documentation page to list all pods,

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.defaultClient();
        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());
        }
    }
}

Hope it helps.

-- Kannaiyan
Source: StackOverflow