Package org.apache.flink.kubernetes.kubeclient.resources

Class KubernetesLeaderElector

java.lang.Object

org.apache.flink.kubernetes.kubeclient.resources.KubernetesLeaderElector

public class KubernetesLeaderElector
extends Object

Represent KubernetesLeaderElector in kubernetes. LeaderElector.run() is a blocking call. It should be run in the IO executor, not the main thread. The lifecycle is bound to single leader election. Once the leadership is revoked, as well as the KubernetesLeaderElector.LeaderCallbackHandler.notLeader() is called, the LeaderElector.run() will finish. To start another round of election, we need to trigger again.

LeaderElector.run() is responsible for creating the leader ConfigMap and continuously update the annotation. The annotation key is LEADER_ANNOTATION_KEY and the value is in the following json format. metadata: annotations: control-plane.alpha.kubernetes.io/leader: '{"holderIdentity":"623e39fb-70c3-44f1-811f-561ec4a28d75","leaseDuration":15.000000000,"acquireTime":"2020-10-20T04:06:31.431000Z","renewTime":"2020-10-22T08:51:36.843000Z","leaderTransitions":37981}'

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	KubernetesLeaderElector.LeaderCallbackHandler	Callback handler for leader election.

Field Summary

Fields

Modifier and Type	Field	Description
static String	LEADER_ANNOTATION_KEY

Constructor Summary

Constructors

Constructor	Description
KubernetesLeaderElector(io.fabric8.kubernetes.client.NamespacedKubernetesClient kubernetesClient, KubernetesLeaderElectionConfiguration leaderConfig, KubernetesLeaderElector.LeaderCallbackHandler leaderCallbackHandler)
KubernetesLeaderElector(io.fabric8.kubernetes.client.NamespacedKubernetesClient kubernetesClient, KubernetesLeaderElectionConfiguration leaderConfig, KubernetesLeaderElector.LeaderCallbackHandler leaderCallbackHandler, ExecutorService executorService)

Method Summary

Modifier and Type	Method	Description
static boolean	hasLeadership(KubernetesConfigMap configMap, String lockIdentity)
void	run()
void	stop()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LEADER_ANNOTATION_KEY

@VisibleForTesting
public static final String LEADER_ANNOTATION_KEY

See Also:

Constant Field Values

Constructor Detail

KubernetesLeaderElector

public KubernetesLeaderElector(io.fabric8.kubernetes.client.NamespacedKubernetesClient kubernetesClient,
                               KubernetesLeaderElectionConfiguration leaderConfig,
                               KubernetesLeaderElector.LeaderCallbackHandler leaderCallbackHandler)

KubernetesLeaderElector

@VisibleForTesting
public KubernetesLeaderElector(io.fabric8.kubernetes.client.NamespacedKubernetesClient kubernetesClient,
                               KubernetesLeaderElectionConfiguration leaderConfig,
                               KubernetesLeaderElector.LeaderCallbackHandler leaderCallbackHandler,
                               ExecutorService executorService)

Method Detail

run

public void run()

stop

public void stop()

hasLeadership

public static boolean hasLeadership(KubernetesConfigMap configMap,
                                    String lockIdentity)