Scale Percona Distribution for MySQL on Kubernetes

One of the great advantages brought by Kubernetes platform is the ease of an application scaling. Scaling an application results in adding or removing the Pods and scheduling them to available Kubernetes nodes.

Size of the cluster is controlled by a size key in the Custom Resource options configuration. That’s why scaling the cluster needs nothing more but changing this option and applying the updated configuration file. This may be done in a specifically saved config, or on the fly, using the following command:

$ kubectl patch ps cluster1 --type='json' -p='[{"op": "replace", "path": "/spec/mysql/size", "value": 5 }]'

In this example we have changed the size of the Percona Server for MySQL Cluster to 5 instances.

Increase the Persistent Volume Claim size

Kubernetes manages storage with a PersistentVolume (PV), a segment of storage supplied by the administrator, and a PersistentVolumeClaim (PVC), a request for storage from a user. In Kubernetes v1.11 the feature was added to allow a user to increase the size of an existing PVC object. The user cannot shrink the size of an existing PVC object. Certain volume types support, by default, expanding PVCs (details about PVCs and the supported volume types can be found in Kubernetes documentation)

The following are the steps to increase the size:

1. Extract and backup the yaml file for the cluster

   kubectl get ps cluster1 -o yaml --export > CR_backup.yaml
   

2. Now you should delete the cluster.

   You can use the following command to delete the cluster:

   $ kubectl delete -f CR_backup.yaml
   

3. For each node, edit the yaml to resize the PVC object.

   $ kubectl edit pvc datadir-cluster1-mysql-0
   

   In the yaml, edit the spec.resources.requests.storage value.

   spec:
     accessModes:
     - ReadWriteOnce
     resources:
       requests:
         storage: 6Gi
   

   Perform the same operation on the other nodes.

   $ kubectl edit pvc datadir-cluster1-mysql-1
   $ kubectl edit pvc datadir-cluster1-mysql-2
   

4. In the CR configuration file, use vim or another text editor to edit the PVC size.

   $ vim CR_backup.yaml
   

5. Apply the updated configuration to the cluster.

   $ kubectl apply -f CR_backup.yaml
   

Contact Us

For free technical help, visit the Percona Community Forum.

To report bugs or submit feature requests, open a JIRA ticket.

For paid support and managed or consulting services , contact Percona Sales.

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Last update: 2023-08-31