How to create Job in Kubernetes using Java API - kubernetes

Question

Am able to create a job in the Kubernetes cluster using CLI (https://kubernetesbyexample.com/jobs/)
Is there a way to create a job inside the cluster using Java API ?

Answer 1

You can use Kubernetes Java Client to create any object such as Job. Referring from the example here
/*
* Creates a simple run to complete job that computes π to 2000 places and prints it out.
*/
public class JobExample {
private static final Logger logger = LoggerFactory.getLogger(JobExample.class);
public static void main(String[] args) {
final ConfigBuilder configBuilder = new ConfigBuilder();
if (args.length > 0) {
configBuilder.withMasterUrl(args[0]);
}
try (KubernetesClient client = new DefaultKubernetesClient(configBuilder.build())) {
final String namespace = "default";
final Job job = new JobBuilder()
.withApiVersion("batch/v1")
.withNewMetadata()
.withName("pi")
.withLabels(Collections.singletonMap("label1", "maximum-length-of-63-characters"))
.withAnnotations(Collections.singletonMap("annotation1", "some-very-long-annotation"))
.endMetadata()
.withNewSpec()
.withNewTemplate()
.withNewSpec()
.addNewContainer()
.withName("pi")
.withImage("perl")
.withArgs("perl", "-Mbignum=bpi", "-wle", "print bpi(2000)")
.endContainer()
.withRestartPolicy("Never")
.endSpec()
.endTemplate()
.endSpec()
.build();
logger.info("Creating job pi.");
client.batch().jobs().inNamespace(namespace).createOrReplace(job);
// Get All pods created by the job
PodList podList = client.pods().inNamespace(namespace).withLabel("job-name", job.getMetadata().getName()).list();
// Wait for pod to complete
client.pods().inNamespace(namespace).withName(podList.getItems().get(0).getMetadata().getName())
.waitUntilCondition(pod -> pod.getStatus().getPhase().equals("Succeeded"), 1, TimeUnit.MINUTES);
// Print Job's log
String joblog = client.batch().jobs().inNamespace(namespace).withName("pi").getLog();
logger.info(joblog);
} catch (KubernetesClientException e) {
logger.error("Unable to create job", e);
} catch (InterruptedException interruptedException) {
logger.warn("Thread interrupted!");
Thread.currentThread().interrupt();
}
}
}

Answer 2

If you want to launch a job using a static manifest yaml from inside the cluster, it should be easy using the official library.
This code worked for me.
ApiClient client = ClientBuilder.cluster().build(); //create in-cluster client
Configuration.setDefaultApiClient(client);
BatchV1Api api = new BatchV1Api(client);
V1Job job = new V1Job();
job = (V1Job) Yaml.load(new File("/tmp/template.yaml")); //load static yaml file
ApiResponse<V1Job> response = api.createNamespacedJobWithHttpInfo("default", job, "true", null, null);
You can also modify any kind of information of the job before launching it with the combination of getter and setter.
// set metadata-name
job.getMetadata().setName("newName");
// set spec-template-metadata-name
job.getSpec().getTemplate().getMetadata().setName("newName");