Add-ons

Run the following command on the destination cluster to create the namespace:

$ kubectl create ns <destination-ns>

Replace destination-ns with a name for the namespace that will contain your destination persistent volume claim.

Copy the following YAML content to create a new file called replication_destination.yaml:

---
apiVersion: volsync.backube/v1alpha1
kind: ReplicationDestination
metadata:
  name: <destination>
  namespace: <destination-ns>
spec:
  rsync:
    serviceType: LoadBalancer
    copyMethod: Snapshot
    capacity: 2Gi
    accessModes: [ReadWriteOnce]
    storageClassName: gp2-csi
    volumeSnapshotClassName: csi-aws-vsc

Note: The capacity value should match the capacity of the persistent volume claim that is being replicated.

Replace destination with the name of your replication destination CR.

Replace destination-ns with the name of the namespace where your destination is located.

For this example, the ServiceType value of LoadBalancer is used. The load balancer service is created by the source cluster to enable your source managed cluster to transfer information to a different destination managed cluster. You can use ClusterIP as the service type if your source and destinations are on the same cluster, or if you have Submariner network service configured. Note the address and the name of the secret to refer to when you configure the source cluster.

The storageClassName and volumeSnapshotClassName are optional parameters. Specify the values for your environment, particularly if you are using a storage class and volume snapshot class name that are different than the default values for your environment.

Run the following command on the destination cluster to create the replicationdestination resource:

$ kubectl create -n <destination-ns> -f replication_destination.yaml

Replace destination-ns with the name of the namespace where your destination is located.

After the replicationdestination resource is created, following parameters and values are added to the resource:

Run the following command to copy the value of .status.rsync.address to use on the source cluster:

$ ADDRESS=`kubectl get replicationdestination <destination> -n <destination-ns> --template={{.status.rsync.address}}`
$ echo $ADDRESS

Replace destination with the name of your replication destination CR.

Replace destination-ns with the name of the namespace where your destination is located.

The output should appear similar to the following output, which is for an Amazon Web Services environment:

a831264645yhrjrjyer6f9e4a02eb2-5592c0b3d94dd376.elb.us-east-1.amazonaws.com

Run the following command to copy the name of the secret and the contents of the secret that are provided as the value of .status.rsync.sshKeys.

$ SSHKEYS=`kubectl get replicationdestination <destination> -n <destination-ns> --template={{.status.rsync.sshKeys}}`
$ echo $SSHKEYS

Replace destination with the name of your replication destination CR.

Replace destination-ns with the name of the namespace where your destination is located.

You will have to enter it on the source cluster when you configure the source. The output should be the name of your SSH keys secret file, which might resemble the following name:

volsync-rsync-dst-src-destination-name

Copy the following YAML content to create a new file called replication_source.yaml on the source cluster:

---
apiVersion: volsync.backube/v1alpha1
kind: ReplicationSource
metadata:
  name: <source>
  namespace: <source-ns>
spec:
  sourcePVC: <persistent_volume_claim>
  trigger:
    schedule: "*/3 * * * *"
  rsync:
    sshKeys: <mysshkeys>
    address: <my.host.com>
    copyMethod: Snapshot
    storageClassName: gp2-csi
    volumeSnapshotClassName: gp2-csi

Replace source with the name for your replication source CR. See step 3-vi of this procedure for instructions on how to replace this automatically.

Replace source-ns with the namespace of the persistent volume claim where your source is located. See step 3-vi of this procedure for instructions on how to replace this automatically.

Replace persistent_volume_claim with the name of your source persistent volume claim.

Replace mysshkeys with the keys that you copied from the .status.rsync.sshKeys field of the ReplicationDestination when you configured it.

Replace my.host.com with the host address that you copied from the .status.rsync.address field of the ReplicationDestination when you configured it.

If your storage driver supports cloning, using Clone as the value for copyMethod might be a more streamlined process for the replication.

StorageClassName and volumeSnapshotClassName are optional parameters. If you are using a storage class and volume snapshot class name that are different than the defaults for your environment, specify those values.

You can now set up the synchronization method of the persistent volume.

Copy the SSH secret from the destination cluster by entering the following command against the destination cluster:

$ kubectl get secret -n <destination-ns> $SSHKEYS -o yaml > /tmp/secret.yaml

Replace destination-ns with the namespace of the persistent volume claim where your destination is located.

Open the secret file in the vi editor by entering the following command:

$ vi /tmp/secret.yaml

In the open secret file on the destination cluster, make the following changes:

On the source cluster, create the secret file by entering the following command on the source cluster:

$ kubectl create -f /tmp/secret.yaml

On the source cluster, modify the replication_source.yaml file by replacing the value of the address and sshKeys in the ReplicationSource object with the values that you noted from the destination cluster by entering the following commands:

$ sed -i "s/<my.host.com>/$ADDRESS/g" replication_source.yaml
$ sed -i "s/<mysshkeys>/$SSHKEYS/g" replication_source.yaml
$ kubectl create -n <source> -f replication_source.yaml

Replace my.host.com with the host address that you copied from the .status.rsync.address field of the ReplicationDestination when you configured it.

Replace mysshkeys with the keys that you copied from the .status.rsync.sshKeys field of the ReplicationDestination when you configured it.

Replace source with the name of the persistent volume claim where your source is located.

Note: You must create the the file in the same namespace as the persistent volume claim that you want to replicate.

Verify that the replication completed by running the following command on the ReplicationSource object:

$ kubectl describe ReplicationSource -n <source-ns> <source>

Replace source-ns with the namespace of the persistent volume claim where your source is located.

Replace source with the name of your replication source CR.

If the replication was successful, the output should be similar to the following example:

Status:
  Conditions:
    Last Transition Time:  2021-10-14T20:48:00Z
    Message:               Synchronization in-progress
    Reason:                SyncInProgress
    Status:                True
    Type:                  Synchronizing
    Last Transition Time:  2021-10-14T20:41:41Z
    Message:               Reconcile complete
    Reason:                ReconcileComplete
    Status:                True
    Type:                  Reconciled
  Last Sync Duration:      5m20.764642395s
  Last Sync Time:          2021-10-14T20:47:01Z
  Next Sync Time:          2021-10-14T20:48:00Z

If the Last Sync Time has no time listed, then the replication is not complete.