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Dynamic Persistence Configuration

6.0-SNAPSHOT 5.5 5.4 5.3 5.2 5.1 5.0

If you want to enable Dynamic Persistence Configuration feature on your cluster, there are few instructions that you must apply in your chart configurations.

The first one is to change the Hazelcast configuration file path to /data/external directory. It can be achieved by initContainers. You also need to provide PersistentVolumeClaim as external volume.

PersistentVolumeClaim sample:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: <PVC Name>
spec:
  storageClassName: <Storage Class>
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
The AccessMode of Persistent Volume has an important role in spreading out pods among nodes in the cluster. \ ReadWriteOnce - the volume can be mounted as read-write by a single node. ReadWriteOnce access mode still can allow multiple pods to access the volume when the pods are running on the same node.\ ReadWriteMany - the volume can be mounted as read-write by many nodes.

Add initContainers, which changes Hazelcast configuration file path, in your values file.

externalVolume:
  persistentVolumeClaim:
    claimName: <PVC Name>
...
initContainers:
  - name: init-container
    image: alpine
    command: ["/bin/sh", "-c", "cp -n /data/hazelcast/hazelcast.yaml /data/external/hazelcast.yaml && chmod 777 /data/external/hazelcast.yaml"]
    volumeMounts:
    - name: hazelcast-external
      mountPath: /data/external/
    - name: hazelcast-storage
      mountPath: /data/hazelcast/

Then, update the new path of Hazelcast configuration file.

hazelcast:
  javaOpts: -Dhazelcast.config=/data/external/hazelcast.yaml

Getting all these instructions together in your values yaml file.

hazelcast:
  licenseKey: <license key>
  yaml:
    hazelcast:
      ...
      dynamic-configuration:
        persistence-enabled: true
        backup-dir: /data/external/backups
  javaOpts: -Dhazelcast.config=/data/external/hazelcast.yaml
externalVolume:
  persistentVolumeClaim:
    claimName: <pvc>
initContainers:
  - name: init-container
    image: alpine
    command: ["/bin/sh", "-c", "cp -n /data/hazelcast/hazelcast.yaml /data/external/hazelcast.yaml && chmod 777 /data/external/hazelcast.yaml"]
    volumeMounts:
    - name: hazelcast-external
      mountPath: /data/external/
    - name: hazelcast-storage
      mountPath: /data/hazelcast/
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