Kubernetes HA Services #
Flink’s Kubernetes HA services use Kubernetes for high availability services.
Kubernetes high availability services can only be used when deploying to Kubernetes. Consequently, they can be configured when using standalone Flink on Kubernetes or the native Kubernetes integration
In order to use Flink’s Kubernetes HA services you must fulfill the following prerequisites:
- Kubernetes >= 1.9.
- Service account with permissions to create, edit, delete ConfigMaps. Take a look at how to configure a service account for Flink’s native Kubernetes integration and standalone Flink on Kubernetes for more information.
In order to start an HA-cluster you have to configure the following configuration keys:
- high-availability.type (required):
high-availability.typeoption has to be set to
- high-availability.storageDir (required):
JobManager metadata is persisted in the file system
high-availability.storageDirand only a pointer to this state is stored in Kubernetes.
storageDir stores all metadata needed to recover a JobManager failure.
- kubernetes.cluster-id (required):
In order to identify the Flink cluster, you have to specify a
Example configuration #
Configure high availability mode in
kubernetes.cluster-id: <cluster-id> high-availability.type: kubernetes high-availability.storageDir: hdfs:///flink/recovery
High availability data clean up #
To keep HA data while restarting the Flink cluster, simply delete the deployment (via
kubectl delete deployment <cluster-id>).
All the Flink cluster related resources will be deleted (e.g. JobManager Deployment, TaskManager pods, services, Flink conf ConfigMap).
HA related ConfigMaps will be retained because they do not set the owner reference.
When restarting the cluster, all previously running jobs will be recovered and restarted from the latest successful checkpoint.