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Kubernetes Client API

Maven Central Javadocs

This library represents a Java Kubernetes client API using JAXRS 2.0.

Add it to your Maven pom.xml

To be able to use the Java code in your Apache Maven based project add this into your pom.xml


Try an example

If you clone the source code:

git clone https://github.com/fabric8io/fabric8.git
cd fabric8

And if you are running Kubernetes (e.g. try run fabric8) so that $KUBERNETES_MASTER is pointing to the Kubernetes REST API then the following should work:

cd components/kubernetes-api
mvn clean test-compile exec:java

The Example program should start and list some pods.

API Overview

You use the DefaultKubernetesClient to create an instance of Kubernetes Client which supports the Kubernetes REST API

For example:

KubernetesClient kube = new DefaultKubernetesClient();
PodList pods = kube.pods().list();
for (Pod pod : pods.getItems()) {
    String name = pod.getMetadata().getName();
    String ip = pod.getStatus().getPodIP();

The KubernetesClient defaults to using the KUBERNETES_MASTER environment variable.

If your Java code is running inside of a Kubernetes environment the KubernetesClient will default to using kubernetes.default.svc (override by setting KUBERNETES_MASTER) as the address to communicate with the kubernetes service for the REST API.

If you wish to use a specific URL in your Java code just pass it into the factory constructor (though usually you don't need to!).

KubernetesClient kube = new DefaultKubernetesClient("http://localhost:8585/");
PodList pods = kube.pods().list();

To see more of the Kubernetes API in action using the Kubernetes Client see this example


All configuration is done via the following environment variables:

  • KUBERNETES_MASTER - the location of the kubernetes master
  • KUBERNETES_NAMESPACE - the default namespace used on operations
  • KUBERNETES_CERTS_CA_DATA - the full Kubernetes CA certificate as a string (only this or KUBERNETES_CERTS_CA_FILE should be specified)
  • KUBERNETES_CERTS_CA_FILE - the path to the Kubernetes CA certificate file (only this or KUBERNETES_CERTS_CA_DATA should be specified)
  • KUBERNETES_CERTS_CLIENT_DATA - the full Kubernetes client certificate as a string (only this or KUBERNETES_CERTS_CLIENT_FILE should be specified)
  • KUBERNETES_CERTS_CLIENT_FILE - the path to the Kubernetes client certificate file (only this or KUBERNETES_CERTS_CLIENT_DATA should be specified)
  • KUBERNETES_CERTS_CLIENT_KEY_DATA - the full Kubernetes client private key as a string (only this or KUBERNETES_CERTS_CLIENT_KEY_FILE should be specified)
  • KUBERNETES_CERTS_CLIENT_KEY_FILE - the path to the Kubernetes client private key file (only this or KUBERNETES_CERTS_CLIENT_KEY_DATA should be specified)
  • KUBERNETES_TRUST_CERTIFICATES - whether to trust the Kubernetes server certificate (this is insecure so please try to configure certificates properly via the other environment variables if at all possible)

The *_DATA variants take precedence over the *_FILE variants.

Defaults from OpenShift

If no configuration is supplied through explicit code or environment variables, the kubernetes-api library will try to find the current login token and namespace by parsing the users ~/.kube/config file.

If needed, you can specify the path to ~/.kube/config with the environment variable KUBECONFIG. (e.g. on Windows, KUBECONFIG=U:\\.kube\\config)

This means that if you use the OpenShift command line tool oc you can login and change projects (namespaces in kubernetes speak) and those will be used by default by the kubernetes-api library.


oc login
oc project cheese
mvn fabric8:apply

In the above, if there is no KUBERNETES_NAMESPACE environment variable or maven property called fabric8.apply.namespace then the fabric8:apply goal will apply the Kubernetes resources to the cheese namespace.