This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Cloud Kubernetes 3.1.3!

Leader Election

The Spring Cloud Kubernetes leader election mechanism implements the leader election API of Spring Integration using a Kubernetes ConfigMap.

Multiple application instances compete for leadership, but leadership will only be granted to one. When granted leadership, a leader application receives an OnGrantedEvent application event with leadership Context. Applications periodically attempt to gain leadership, with leadership granted to the first caller. A leader will remain a leader until either it is removed from the cluster, or it yields its leadership. When leadership removal occurs, the previous leader receives OnRevokedEvent application event. After removal, any instances in the cluster may become the new leader, including the old leader.

To include it in your project, add the following dependency. Fabric8 Leader Implementation

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-kubernetes-fabric8-leader</artifactId>
</dependency>

To specify the name of the configmap used for leader election use the following property.

spring.cloud.kubernetes.leader.config-map-name=leader