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Run MariaDB with Custom PodTemplate

KubeDB supports providing custom configuration for MariaDB via PodTemplate. This tutorial will show you how to use KubeDB to run a MariaDB database with custom configuration using PodTemplate.

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.

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

    $ kubectl create ns demo
    namespace/demo created
    

Note: YAML files used in this tutorial are stored in docs/examples/mysql folder in GitHub repository kubedb/docs.

Overview

KubeDB allows providing a template for database pod through spec.podTemplate. KubeDB operator will pass the information provided in spec.podTemplate to the StatefulSet created for MariaDB database.

KubeDB accept following fields to set in spec.podTemplate:

  • metadata:
    • annotations (pod’s annotation)
  • controller:
    • annotations (statefulset’s annotation)
  • spec:
    • env
    • resources
    • initContainers
    • imagePullSecrets
    • nodeSelector
    • affinity
    • schedulerName
    • tolerations
    • priorityClassName
    • priority
    • securityContext

Read about the fields in details in PodTemplate concept,

CRD Configuration

Below is the YAML for the MariaDB created in this example. Here, spec.podTemplate.spec.env specifies environment variables and spec.podTemplate.spec.args provides extra arguments for MariaDB Docker Image.

In this tutorial, an initial database mdDB will be created by providing env MYSQL_DATABASE while the server character set will be set to utf8mb4 by adding extra args.

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
  podTemplate:
    spec:
      env:
      - name: MYSQL_DATABASE
        value: mdDB
      args:
      - --character-set-server=utf8mb4
      resources:
        requests:
          memory: "1Gi"
          cpu: "250m"
  terminationPolicy: WipeOut
$ kubectl create -f https://github.com/kubedb/docs/raw/v2021.04.16/docs/guides/mariadb/configuration/using-pod-template/examples/md-misc-config.yaml
mariadb.kubedb.com/sample-mariadb created

Now, wait a few minutes. KubeDB operator will create necessary PVC, statefulset, services, secret etc. If everything goes well, we will see that a pod with the name sample-mariadb has been created.

Check that the statefulset’s pod is running

$ $ kubectl get pod -n demo
NAME               READY   STATUS    RESTARTS   AGE
sample-mariadb-0   1/1     Running   0          96s

Check the pod’s log to see if the database is ready

$ kubectl logs -f -n demo sample-mariadb-0
2021-03-18 06:06:17+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 1:10.5.8+maria~focal started.
2021-03-18 06:06:18+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
2021-03-18 06:06:18+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 1:10.5.8+maria~focal started.
2021-03-18 06:06:19+00:00 [Note] [Entrypoint]: Initializing database files
...
2021-03-18  6:06:33 0 [Note] mysqld: ready for connections.
Version: '10.5.8-MariaDB-1:10.5.8+maria~focal'  socket: '/run/mysqld/mysqld.sock'  port: 3306  mariadb.org binary distribution

Once we see Note] mysqld: ready for connections. in the log, the database is ready.

Now, we will check if the database has started with the custom configuration we have provided.

$ kubectl exec -it -n demo sample-mariadb-0 -- bash
[email protected]:/ mysql -u${MYSQL_ROOT_USERNAME} -p${MYSQL_ROOT_PASSWORD}
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 22
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.

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

# Check character_set_server
MariaDB [(none)]> show variables like 'char%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | latin1                     |
| character_set_connection | latin1                     |
| character_set_database   | utf8mb4                    |
| character_set_filesystem | binary                     |
| character_set_results    | latin1                     |
| character_set_server     | utf8mb4                    |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.001 sec)

MariaDB [(none)]> quit;
Bye

Cleaning up

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

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