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MariaDB QuickStart

This tutorial will show you how to use KubeDB to run a MariaDB database.

Note: The yaml files used in this tutorial are stored in here.

Before You Begin

• At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.

• Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.

• StorageClass is required to run KubeDB. Check the available StorageClass in cluster.

$ kubectl get storageclasses
NAME                 PROVISIONER             RECLAIMPOLICY     VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
standard (default)   rancher.io/local-path   Delete            WaitForFirstConsumer   false                  6h22m

• To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Find Available MariaDBVersion

When you have installed KubeDB, it has created MariaDBVersion crd for all supported MariaDB versions. Check it by using the following command,

$ kubectl get mariadbversions
NAME      VERSION   DB_IMAGE                 DEPRECATED   AGE
10.4.17   10.4.17   kubedb/mariadb:10.4.17                15h
10.5.8    10.5.8    kubedb/mariadb:10.5.8                 15h

Create a MariaDB database

KubeDB implements a MariaDB CRD to define the specification of a MariaDB database. Below is the MariaDB object created in this tutorial.

apiVersion: kubedb.com/v1alpha2
kind: MariaDB
metadata:
  name: sample-mariadb
  namespace: demo
spec:
  version: "10.5.8"
  storageType: Durable
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  terminationPolicy: WipeOut

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.12.21/docs/guides/mariadb/quickstart/overview/examples/sample-mariadb.yaml
mariadb.kubedb.com/sample-mariadb created

Here,

• spec.version is the name of the MariaDBVersion CRD where the docker images are specified. In this tutorial, a MariaDB 10.5.8 database is going to create.
• spec.storageType specifies the type of storage that will be used for MariaDB database. It can be Durable or Ephemeral. Default value of this field is Durable. If Ephemeral is used then KubeDB will create MariaDB database using EmptyDir volume. In this case, you don’t have to specify spec.storage field. This is useful for testing purposes.
• spec.storage specifies the StorageClass of PVC dynamically allocated to store data for this database. This storage spec will be passed to the StatefulSet created by KubeDB operator to run database pods. You can specify any StorageClass available in your cluster with appropriate resource requests.
• spec.terminationPolicy gives flexibility whether to nullify(reject) the delete operation of MariaDB crd or which resources KubeDB should keep or delete when you delete MariaDB crd. If admission webhook is enabled, It prevents users from deleting the database as long as the spec.terminationPolicy is set to DoNotTerminate.

Note: spec.storage section is used to create PVC for database pod. It will create PVC with storage size specified instorage.resources.requests field. Don’t specify limits here. PVC does not get resized automatically.

KubeDB operator watches for MariaDB objects using Kubernetes api. When a MariaDB object is created, KubeDB operator will create a new StatefulSet and a Service with the matching MariaDB object name. KubeDB operator will also create a governing service for StatefulSets with the name kubedb, if one is not already present.

$ kubectl describe -n demo mariadb sample-mariadb
Name:         sample-mariadb
Namespace:    demo
Labels:       <none>
Annotations:  API Version:  kubedb.com/v1alpha2
Kind:         MariaDB
Metadata:
  Creation Timestamp:  2021-03-10T04:31:09Z
  Finalizers:
    kubedb.com
  ...  
Spec:
  Auth Secret:
    Name:  sample-mariadb-auth
  ...
  Storage:
    Access Modes:
      ReadWriteOnce
    Resources:
      Requests:
        Storage:         1Gi
    Storage Class Name:  standard
  Storage Type:          Durable
  Termination Policy:    WipeOut
  Version:               10.5.8
Status:
  Conditions:
    Last Transition Time:  2021-03-10T04:31:09Z
    Message:               The KubeDB operator has started the provisioning of MariaDB: demo/sample-mariadb
    Reason:                DatabaseProvisioningStartedSuccessfully
    Status:                True
    Type:                  ProvisioningStarted
    Last Transition Time:  2021-03-10T04:31:19Z
    Message:               The MariaDB: demo/sample-mariadb is accepting client requests.
    Observed Generation:   2
    Reason:                DatabaseAcceptingConnectionRequest
    Status:                True
    Type:                  AcceptingConnection
    Last Transition Time:  2021-03-10T04:32:49Z
    Message:               The MySQL: demo/sample-mariadb is ready.
    Observed Generation:   2
    Reason:                ReadinessCheckSucceeded
    Status:                True
    Type:                  Ready
    Last Transition Time:  2021-03-10T04:32:39Z
    Message:               All desired replicas are ready.
    Reason:                AllReplicasReady
    Status:                True
    Type:                  ReplicaReady
    Last Transition Time:  2021-03-10T04:32:49Z
    Message:               The MariaDB: demo/sample-mariadb is successfully provisioned.
    Observed Generation:   2
    Reason:                DatabaseSuccessfullyProvisioned
    Status:                True
    Type:                  Provisioned
  Observed Generation:     2
  Phase:                   Ready
Events:
  Type    Reason      Age   From              Message
  ----    ------      ----  ----              -------
  Normal  Successful  21m   MariaDB operator  Successfully created governing service
  Normal  Successful  21m   MariaDB operator  Successfully created Service
  Normal  Successful  21m   MariaDB operator  Successfully created StatefulSet demo/sample-mariadb
  Normal  Successful  21m   MariaDB operator  Successfully created appbinding
  Normal  Successful  21m   MariaDB operator  Successfully patched governing service
  Normal  Successful  21m   MariaDB operator  Successfully patched StatefulSet demo/sample-mariadb
  
  
$ kubectl get statefulset -n demo
NAME             READY   AGE
sample-mariadb   1/1     27m

$ kubectl get pvc -n demo
NAME                    STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
data-sample-mariadb-0   Bound    pvc-10651900-d975-467f-80ff-9c4755bdf917   1Gi        RWO            standard       27m

$ kubectl get pv -n demo
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                        STORAGECLASS   REASON   AGE
pvc-10651900-d975-467f-80ff-9c4755bdf917   1Gi        RWO            Delete           Bound    demo/data-sample-mariadb-0   standard                27m

$ kubectl get service -n demo
NAME                  TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
sample-mariadb        ClusterIP   10.105.207.172   <none>        3306/TCP   28m
sample-mariadb-pods   ClusterIP   None             <none>        3306/TCP   28m

KubeDB operator sets the status.phase to Running once the database is successfully created. Run the following command to see the modified MariaDB object:

$ kubectl get mariadb -n demo sample-mariadb -o yaml
apiVersion: kubedb.com/v1alpha2
kind: MariaDB
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"kubedb.com/v1alpha2","kind":"MariaDB","metadata":{"annotations":{},"name":"sample-mariadb","namespace":"demo"},"spec":{"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"storageType":"Durable","terminationPolicy":"WipeOut","version":"10.5.8"}}      
  creationTimestamp: "2021-03-10T04:31:09Z"
  finalizers:
  - kubedb.com
  generation: 2
  ...
  name: sample-mariadb
  namespace: demo
  resourceVersion: "7952"
  selfLink: /apis/kubedb.com/v1alpha2/namespaces/demo/mariadbs/sample-mariadb
  uid: 412a4739-ac65-4b5a-a943-5e148f3222b1
spec:
  authSecret:
    name: sample-mariadb-auth
  ...
  replicas: 1
  storage:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
    storageClassName: standard
  storageType: Durable
  terminationPolicy: WipeOut
  version: 10.5.8
status:
  observedGeneration: 2
  phase: Ready

Connect with MariaDB database

KubeDB operator has created a new Secret called mariadb-quickstart-auth (format: {mariadb-object-name}-auth) for storing the password for mariadb superuser. This secret contains a username key which contains the username for MariaDB superuser and a password key which contains the password for MariaDB superuser.

If you want to use an existing secret please specify that when creating the MariaDB object using spec.authSecret.name. While creating this secret manually, make sure the secret contains these two keys containing data username and password and also make sure of using root as value of username.

Now, we need username and password to connect to this database from kubeclt exec command. In this example, sample-mariadb-auth secret holds username and password.

$ kubectl get secrets -n demo sample-mariadb-auth -o jsonpath='{.data.\username}' | base64 -d
root

$ kubectl get secrets -n demo sample-mariadb-auth -o jsonpath='{.data.\password}' | base64 -d
w*yOU$b53dTbjsjJ

We will exec into the pod sample-mariadb-0 and conncet to the database using username and password.

$ kubectl exec -it -n demo sample-mariadb-0 -- mariadb -u root --password='w*yOU$b53dTbjsjJ'
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 335
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
3 rows in set (0.001 sec)

Database TerminationPolicy

This field is used to regulate the deletion process of the related resources when MariaDB object is deleted. User can set the value of this field according to their needs. The available options and their use case scenario is described below:

DoNotTerminate:

When terminationPolicy is set to DoNotTerminate, KubeDB takes advantage of ValidationWebhook feature in Kubernetes 1.9.0 or later clusters to implement DoNotTerminate feature. If admission webhook is enabled, It prevents users from deleting the database as long as the spec.terminationPolicy is set to DoNotTerminate. If you create a database with terminationPolicy DoNotTerminate and try to delete it, you will see this:

$ kubectl delete mariadb sample-mariadb -n demo
Error from server (BadRequest): admission webhook "mariadb.validators.kubedb.com" denied the request: mariadb "mariadb-quickstart" can't be halted. To delete, change spec.terminationPolicy

Now, run kubectl edit mariadb sample-mariadb -n demo to set spec.terminationPolicy to Halt (which deletes the mariadb object and keeps PVC, snapshots, Secrets intact) or remove this field (which default to Delete). Then you will be able to delete/halt the database.

Halt:

Suppose you want to reuse your database volume and credential to deploy your database in future using the same configurations. But, right now you just want to delete the database except the database volumes and credentials. In this scenario, you must set the MariaDB object terminationPolicy to Halt.

When the TerminationPolicy is set to Halt and the MariaDB object is deleted, the KubeDB operator will delete the StatefulSet and its pods but leaves the PVCs, secrets and database backup data(snapshots) intact. You can set the terminationPolicy to Halt in existing database using edit command for testing.

At first, run kubectl edit mariadb sample-mariadb -n demo to set spec.terminationPolicy to Halt. Then delete the mariadb object,

$ kubectl delete mariadb sample-mariadb -n demo
mariadb.kubedb.com "sample-mariadb" deleted

Now, run the following command to get all mariadb resources in demo namespaces,

$ kubectl get sts,svc,secret,pvc -n demo
NAME                         TYPE                                  DATA   AGE
secret/default-token-w2pgw   kubernetes.io/service-account-token   3      31m
secret/sample-mariadb-auth   kubernetes.io/basic-auth              2      39s

NAME                                          STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/data-sample-mariadb-0   Bound    pvc-7502c222-2b02-4363-9027-91ab0e7b76dc   1Gi        RWO            standard       39s

From the above output, you can see that all mariadb resources(StatefulSet, Service, etc.) are deleted except PVC and Secret. You can recreate your mariadb again using this resources.

Delete:

If you want to delete the existing database along with the volumes used, but want to restore the database from previously taken snapshots and secrets then you might want to set the MariaDB object terminationPolicy to Delete. In this setting, StatefulSet and the volumes will be deleted. If you decide to restore the database, you can do so using the snapshots and the credentials.

When the TerminationPolicy is set to Delete and the MariaDB object is deleted, the KubeDB operator will delete the StatefulSet and its pods along with PVCs but leaves the secret and database backup data(snapshots) intact.

Suppose, we have a database with terminationPolicy set to Delete. Now, are going to delete the database using the following command:

$ kubectl delete mariadb sample-mariadb -n demo
mariadb.kubedb.com "sample-mariadb" deleted

Now, run the following command to get all mariadb resources in demo namespaces,

$ kubectl get sts,svc,secret,pvc -n demo
NAME                         TYPE                                  DATA   AGE
secret/default-token-w2pgw   kubernetes.io/service-account-token   3      31m
secret/sample-mariadb-auth   kubernetes.io/basic-auth              2      39s

From the above output, you can see that all mariadb resources(StatefulSet, Service, PVCs etc.) are deleted except Secret. You can initialize your mariadb using snapshots(if previously taken) and secret.

If you don’t set the terminationPolicy then the kubeDB set the TerminationPolicy to Delete by-default.

WipeOut:

You can totally delete the MariaDB database and relevant resources without any tracking by setting terminationPolicy to WipeOut. KubeDB operator will delete all relevant resources of this MariaDB database (i.e, PVCs, Secrets, Snapshots) when the terminationPolicy is set to WipeOut.

Suppose, we have a database with terminationPolicy set to WipeOut. Now, are going to delete the database using the following command:

$ kubectl delete mariadb sample-mariadb -n demo
mariadb.kubedb.com "sample-mariadb" deleted

Now, run the following command to get all mariadb resources in demo namespaces,

$ kubectl get sts,svc,secret,pvc -n demo
No resources found in demo namespace.

From the above output, you can see that all mariadb resources are deleted. there is no option to recreate/reinitialize your database if terminationPolicy is set to Delete.

Be careful when you set the terminationPolicy to Delete. Because there is no option to trace the database resources if once deleted the database.

Database Halted

If you want to delete MariaDB resources(StatefulSet,Service, etc.) without deleting the MariaDB object, PVCs and Secret you have to set the spec.halted to true. KubeDB operator will be able to delete the MariaDB related resources except the MariaDB object, PVCs and Secret.

Suppose we have a database running mariadb-quickstart in our cluster. Now, we are going to set spec.halted to true in MariaDB object by running kubectl edit -n demo mariadb-quickstart command.

Run the following command to get MariaDB resources,

$ kubectl get mariadb,sts,secret,svc,pvc -n demo
NAME                                VERSION   STATUS   AGE
mariadb.kubedb.com/mariadb-quickstart   10.5.8    Halted   22m

NAME                           TYPE                                  DATA   AGE
secret/default-token-lgbjm     kubernetes.io/service-account-token   3      27h
secret/mariadb-quickstart-auth   Opaque                                2      22m

NAME                                            STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/data-mariadb-quickstart-0   Bound    pvc-7ab0ebb0-bb2e-45c1-9af1-4f175672605b   1Gi        RWO            standard       22m

From the above output , you can see that MariaDB object, PVCs, Secret are still alive. Then you can recreate your MariaDB with same configuration.

When you set spec.halted to true in MariaDB object then the terminationPolicy is also set to Halt by KubeDB operator.

Cleaning up

To cleanup the Kubernetes resources created by this tutorial, run:

kubectl delete -n demo mariadb/sample-mariadb

kubectl delete ns demo

Tips for Testing

If you are just testing some basic functionalities, you might want to avoid additional hassles due to some safety features that are great for production environment. You can follow these tips to avoid them.

1. Use storageType: Ephemeral. Databases are precious. You might not want to lose your data in your production environment if database pod fail. So, we recommend to use spec.storageType: Durable and provide storage spec in spec.storage section. For testing purpose, you can just use spec.storageType: Ephemeral. KubeDB will use emptyDir for storage. You will not require to provide spec.storage section.
2. Use terminationPolicy: WipeOut. It is nice to be able to delete everything created by KubeDB for a particular MariaDB crd when you delete the crd.

Next Steps

• Want to hack on KubeDB? Check our contribution guidelines.