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MariaDB Volume Expansion
This guide will show you how to use KubeDB Enterprise operator to expand the volume of a MariaDB.
Before You Begin
At first, you need to have a Kubernetes cluster, and the
kubectlcommand-line tool must be configured to communicate with your cluster.You must have a
StorageClassthat supports volume expansion.Install
KubeDBCommunity and Enterprise operator in your cluster following the steps here.You should be familiar with the following
KubeDBconcepts:
To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Expand Volume of MariaDB
Here, we are going to deploy a MariaDB cluster using a supported version by KubeDB operator. Then we are going to apply MariaDBOpsRequest to expand its volume. The process of expanding MariaDB standalone is same as MariaDB cluster.
Prepare MariaDB Database
At first verify that your cluster has a storage class, that supports volume expansion. Let’s check,
$ kubectl get storageclass
NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE
standard (default) rancher.io/local-path Delete WaitForFirstConsumer false 69s
topolvm-provisioner topolvm.cybozu.com Delete WaitForFirstConsumer true 37s
We can see from the output the topolvm-provisioner storage class has ALLOWVOLUMEEXPANSION field as true. So, this storage class supports volume expansion. We will use this storage class. You can install topolvm from here.
Now, we are going to deploy a MariaDB database of 3 replicas with version 10.5.23.
Deploy MariaDB
In this section, we are going to deploy a MariaDB Cluster with 1GB volume. Then, in the next section we will expand its volume to 2GB using MariaDBOpsRequest CRD. Below is the YAML of the MariaDB CR that we are going to create,
apiVersion: kubedb.com/v1
kind: MariaDB
metadata:
name: sample-mariadb
namespace: demo
spec:
version: "10.5.23"
replicas: 3
storageType: Durable
storage:
storageClassName: "topolvm-provisioner"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
deletionPolicy: WipeOut
Let’s create the MariaDB CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.8.21/docs/guides/mariadb/volume-expansion/volume-expansion/example/sample-mariadb.yaml
mariadb.kubedb.com/sample-mariadb created
Now, wait until sample-mariadb has status Ready. i.e,
$ kubectl get mariadb -n demo
NAME VERSION STATUS AGE
sample-mariadb 10.5.23 Ready 5m4s
Let’s check volume size from petset, and from the persistent volume,
$ kubectl get sts -n demo sample-mariadb -o json | jq '.spec.volumeClaimTemplates[].spec.resources.requests.storage'
"1Gi"
$ kubectl get pv -n demo
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-331335d1-c8e0-4b73-9dab-dae57920e997 1Gi RWO Delete Bound demo/data-sample-mariadb-0 topolvm-provisioner 63s
pvc-b90179f8-c40a-4273-ad77-74ca8470b782 1Gi RWO Delete Bound demo/data-sample-mariadb-1 topolvm-provisioner 62s
pvc-f72411a4-80d5-4d32-b713-cb30ec662180 1Gi RWO Delete Bound demo/data-sample-mariadb-2 topolvm-provisioner 62s
You can see the petset has 1GB storage, and the capacity of all the persistent volumes are also 1GB.
We are now ready to apply the MariaDBOpsRequest CR to expand the volume of this database.
Volume Expansion
Here, we are going to expand the volume of the MariaDB cluster.
Create MariaDBOpsRequest
In order to expand the volume of the database, we have to create a MariaDBOpsRequest CR with our desired volume size. Below is the YAML of the MariaDBOpsRequest CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: MariaDBOpsRequest
metadata:
name: md-online-volume-expansion
namespace: demo
spec:
type: VolumeExpansion
databaseRef:
name: sample-mariadb
volumeExpansion:
mode: "Online"
mariadb: 2Gi
Here,
spec.databaseRef.namespecifies that we are performing volume expansion operation onsample-mariadbdatabase.spec.typespecifies that we are performingVolumeExpansionon our database.spec.volumeExpansion.mariadbspecifies the desired volume size.spec.volumeExpansion.modespecifies the desired volume expansion mode (OnlineorOffline). Storageclasstopolvm-provisionersupportsOnlinevolume expansion.
Note: If the Storageclass you are using doesn’t support
OnlineVolume Expansion, Try offline volume expansion by usingspec.volumeExpansion.mode:"Offline".
Let’s create the MariaDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.8.21/docs/guides/mariadb/volume-expansion/volume-expansion/example/online-volume-expansion.yaml
mariadbopsrequest.ops.kubedb.com/md-online-volume-expansion created
Verify MariaDB volume expanded successfully
If everything goes well, KubeDB Enterprise operator will update the volume size of MariaDB object and related PetSets and Persistent Volumes.
Let’s wait for MariaDBOpsRequest to be Successful. Run the following command to watch MariaDBOpsRequest CR,
$ kubectl get mariadbopsrequest -n demo
NAME TYPE STATUS AGE
md-online-volume-expansion VolumeExpansion Successful 96s
We can see from the above output that the MariaDBOpsRequest has succeeded. If we describe the MariaDBOpsRequest we will get an overview of the steps that were followed to expand the volume of the database.
$ kubectl describe mariadbopsrequest -n demo md-online-volume-expansion
Name: md-online-volume-expansion
Namespace: demo
Labels: <none>
Annotations: API Version: ops.kubedb.com/v1alpha1
Kind: MariaDBOpsRequest
Metadata:
UID: 09a119aa-4f2a-4cb4-b620-2aa3a514df11
Spec:
Database Ref:
Name: sample-mariadb
Type: VolumeExpansion
Volume Expansion:
Mariadb: 2Gi
Mode: Online
Status:
Conditions:
Last Transition Time: 2022-01-07T06:38:29Z
Message: Controller has started to Progress the MariaDBOpsRequest: demo/md-online-volume-expansion
Observed Generation: 1
Reason: OpsRequestProgressingStarted
Status: True
Type: Progressing
Last Transition Time: 2022-01-07T06:39:49Z
Message: Online Volume Expansion performed successfully in MariaDB pod for MariaDBOpsRequest: demo/md-online-volume-expansion
Observed Generation: 1
Reason: SuccessfullyVolumeExpanded
Status: True
Type: VolumeExpansion
Last Transition Time: 2022-01-07T06:39:49Z
Message: Controller has successfully expand the volume of MariaDB demo/md-online-volume-expansion
Observed Generation: 1
Reason: OpsRequestProcessedSuccessfully
Status: True
Type: Successful
Observed Generation: 3
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 2m1s KubeDB Enterprise Operator Start processing for MariaDBOpsRequest: demo/md-online-volume-expansion
Normal Starting 2m1s KubeDB Enterprise Operator Pausing MariaDB databse: demo/sample-mariadb
Normal Successful 2m1s KubeDB Enterprise Operator Successfully paused MariaDB database: demo/sample-mariadb for MariaDBOpsRequest: md-online-volume-expansion
Normal Successful 41s KubeDB Enterprise Operator Online Volume Expansion performed successfully in MariaDB pod for MariaDBOpsRequest: demo/md-online-volume-expansion
Normal Starting 41s KubeDB Enterprise Operator Updating MariaDB storage
Normal Successful 41s KubeDB Enterprise Operator Successfully Updated MariaDB storage
Normal Starting 41s KubeDB Enterprise Operator Resuming MariaDB database: demo/sample-mariadb
Normal Successful 41s KubeDB Enterprise Operator Successfully resumed MariaDB database: demo/sample-mariadb
Normal Successful 41s KubeDB Enterprise Operator Controller has Successfully expand the volume of MariaDB: demo/sample-mariadb
Now, we are going to verify from the Petset, and the Persistent Volumes whether the volume of the database has expanded to meet the desired state, Let’s check,
$ kubectl get sts -n demo sample-mariadb -o json | jq '.spec.volumeClaimTemplates[].spec.resources.requests.storage'
"2Gi"
$ kubectl get pv -n demo
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-331335d1-c8e0-4b73-9dab-dae57920e997 2Gi RWO Delete Bound demo/data-sample-mariadb-0 topolvm-provisioner 12m
pvc-b90179f8-c40a-4273-ad77-74ca8470b782 2Gi RWO Delete Bound demo/data-sample-mariadb-1 topolvm-provisioner 12m
pvc-f72411a4-80d5-4d32-b713-cb30ec662180 2Gi RWO Delete Bound demo/data-sample-mariadb-2 topolvm-provisioner 12m
The above output verifies that we have successfully expanded the volume of the MariaDB database.
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
$ kubectl delete mariadb -n demo sample-mariadb
$ kubectl delete mariadbopsrequest -n demo md-online-volume-expansion