Configuring WAN Replication

WAN Replication allows you to keep Hazelcast clusters in sync across multiple sites or cloud deployments. In Hazelcast Platform Operator, you can create a WanReplication resource to replicate a map from a source to a target Hazelcast cluster.

See WAN replication for more detailed information about the configuration and behavior of WAN replication in Hazelcast.

Prerequisites for WAN Replication

Before you create and configure a WanReplication resource, you need to create the following:

A Hazelcast resource and Map resource for the source Hazelcast cluster.
A target Hazelcast cluster that is accessible from the source cluster.

Configuring the WanReplication Resource

You can use the following configuration options in your WanReplication resource. For more detailed information, see the API Reference.

Field Description

Field	Description
`mapResourceName`	The name of the custom `Map` resource to which WAN replication applies.
`targetClusterName`	The name of the Hazelcast cluster that is the target of replication.
`endpoints`	A comma-separated list of the addresses of the Hazelcast members in the target cluster.
`queue`	The configuration of the WAN events queue, which includes two related parameters: `capacity`: The total capacity of WAN events queue. The `fullBehavior` is triggered when the number of events exceeds this limit. `fullBehavior`: What happens to new events that arrive after the events queue is full.
`batch`	How WAN replication events are batched. `size`: The maximum batch size. `maximumDelay`: If the batch size is not reached, the events will be sent after the maximum delay (in milliseconds).
`acknowledgement`	Configuration of the acknowledgement sent after a batch of replication events is received by the target cluster: `type`: Whether an acknowledgement is sent as soon as the batch of events is received (`ACK_ON_RECEIPT`) or after each update is applied to the target cluster (`ACK_ON_OPERATION_COMPLETE`). `timeout`: The period of time the source cluster waits for the acknowledgement. If the confirmation is not received before the timeout, the replication events are resent.

mapResourceName

The name of the custom Map resource to which WAN replication applies.

targetClusterName

The name of the Hazelcast cluster that is the target of replication.

endpoints

A comma-separated list of the addresses of the Hazelcast members in the target cluster.

queue

The configuration of the WAN events queue, which includes two related parameters:

capacity: The total capacity of WAN events queue. The fullBehavior is triggered when the number of events exceeds this limit.
fullBehavior: What happens to new events that arrive after the events queue is full.

batch

How WAN replication events are batched.

size: The maximum batch size.
maximumDelay: If the batch size is not reached, the events will be sent after the maximum delay (in milliseconds).

acknowledgement

Configuration of the acknowledgement sent after a batch of replication events is received by the target cluster:

type: Whether an acknowledgement is sent as soon as the batch of events is received (ACK_ON_RECEIPT) or after each update is applied to the target cluster (ACK_ON_OPERATION_COMPLETE).
timeout: The period of time the source cluster waits for the acknowledgement. If the confirmation is not received before the timeout, the replication events are resent.

Example Configuration

The following WanReplication resource creates the WAN replication configuration for the Hazelcast and Map resources on the source Hazelcast cluster.

Example configuration

apiVersion: hazelcast.com/v1alpha1
kind: WanReplication
metadata:
  name: wanreplication-sample
spec:
  mapResourceName: map-sample
  targetClusterName: dev
  endpoints: "35.192.33.252,35.192.33.255"
  queue:
    capacity: 10000
    fullBehavior: DISCARD_AFTER_MUTATION
  batch:
    size: 500
    maximumDelay: 1000
  acknowledgement:
    type: ACK_ON_OPERATION_COMPLETE
    timeout: 60000

Checking the Status of a WAN Replication

After creating the WanReplication resource, run the following command to find out the WAN replication status:

kubectl get wanreplication wanreplication-sample -o wide

The returned status message will look something like this:

NAME                     STATUS    MESSAGE
wanreplication-sample    Success

You can also monitor the status of the WAN replications in Management Center.