Mysql Service With K3s on Raspberry Pi

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Dependences

  • Installed K3s on a Raspberry Pi[^1]
  • Installed kubectl on your local computer.
  • A MySQL client. (for testing)

Install MySQL on Kubernetes

We will create configures and apply them to create a MySQL service. All configure files below must be applied after created with command:

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kubectl apply -f <config-name>.yaml

All commands below are omitted.

Prepare MySQL Data Storage

Let us create a volume for our MySQL service to store data.[^2]

At first, we need create a directory on node with command:

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mkdir /mnt/data

Then, create a configure file for persistent volume.

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# pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-data-pv-volume
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 2Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"  # the directory created on node

After created, we can claim it on Kubernetes. Here is the config file:

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# pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-data-pv-claim
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi  # the storage should be less than capacity in persistent volume

Adding A Secret with MySQL Password

The passsword of mysql we will use later should be injected into the pod environment by using the Secret.

Note that the value must be encoded using base64[^3].

Says that the password is “mypassword”.

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echo -n 'mypassword' | base64

The output bXlwYXNzd29yZA== should be put into our secret configure file.

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# secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: mysql-secret
type: Opaque
data:
  password: bXlwYXNzd29yZA==  # encoded base64 password

Creating Deployment with a MySQL Container

  • Specifying image to create a container in pod.
  • Using PersistentVolumeClaim as volume.
  • Using Secret as environment variables.
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# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql-deployment
  labels:
    app: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      volumes:
        - name: mysql-data-storage
          persistentVolumeClaim:
            claimName: mysql-data-pv-claim
      containers:
        - name: mysql-container
          image: jsurf/rpi-mariadb
          ports:
            - containerPort: 3306
              name: "mysql-port"
          env:
            - name: MYSQL_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mysql-secret
                  key: password
          volumeMounts:
            - mountPath: "/var/lib/mysql"
              name: mysql-data-storage

Expose the Service

After the deployment applied and the pod is running. The MySQL service is not exposed to the node. We need to create a Service to listen the port on node.

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# service.yaml
apiVersion: v1
kind: Service
metadata:
  name: mysql-service
spec:
  type: NodePort
  selector:
    app: mysql
  ports:
    - protocol: TCP
      port: 3306
      targetPort: 3306
      nodePort: 30006

Have a Try

Now, you can connet to your new database with a MySQL client.

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mysql -P 30006 -h <raspberry-pi-host> -u root -p

All done!

[^1]: An article can help for your installation.
[^2]: You can reference here to configure persistent volume storage.
[^3]: Follow the example in the official document.