Denis

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By Denis Nuțiu

2 minute read

Introduction

Hello 👋,

In this quick tutorial 💻 we’ll explore how to use Volumes and PersistentVolumes with hostpath storage in Microk8s.

We will deploy a simple nginx instance and mount a volume inside it that points to the ~/Downloads folder.

Let’s get started!

Note: The following image was generated with Stable Diffusion

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How-To

You can follow along if you want to setup a quick deployment with a host path volume.

Persistent Volume

Let’s start by creating a Persistent Volume resource:

k apply -f persistent-volume.yaml
apiVersion: v1kind: PersistentVolumemetadata:  name: nuculabs-persistent-volume  labels:    app: nginx    owner: dnutiu    name: tutorial-volumespec:  storageClassName: microk8s-hostpath  # Exclusive to PVC  claimRef:    name: nuculabs-persistent-volume-claim    namespace: default  capacity:    storage: 1Gi  accessModes:    - ReadWriteMany  hostPath:    path: "/home/denis/Downloads"

After applying the file you should see:

➜  Downloads k apply -f persistent_volume.yml persistentvolume/nuculabs-persistent-volume created➜  Downloads k get pvNAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                                      STORAGECLASS        REASON   AGEnuculabs-persistent-volume                 1Gi        RWX            Retain           Available   default/nuculabs-persistent-volume-claim   microk8s-hostpath            5s

The created persistent volume is exclusive to the PersistentVolumeClaim we’ll create next.

Persistent Volume Claim

To reserve the nuculabs-persistent-volume Persistent Volume we need to create a claim:

k apply -f persistent-volume-claim.yaml
apiVersion: v1kind: PersistentVolumeClaimmetadata:  name: nuculabs-persistent-volume-claim  namespace: default  labels:    app: nginx    owner: dnutiu    name: tutorial-volumespec:  storageClassName: "microk8s-hostpath"  volumeName: nuculabs-persistent-volume  accessModes:    - ReadWriteMany  resources:    requests:      storage: 500Gi

We can ensure that the claim is bound to our PV by referencing the volumeName:

spec:  storageClassName: "microk8s-hostpath"  volumeName: nuculabs-persistent-volume

or by using the matchLabels selector:

spec:  storageClassName: "microk8s-hostpath"  selector:    matchLabels:      app: nginx      owner: dnutiu      name: tutorial-volume

To verify that the volume is bound run:

k get pvNAME  STATUS   CLAIM  nuculabs-persistent-volume ...        Bound    default/nuculabs-persistent-volume-claim

It should list the volume name along with the Bound status.

If you’re following along, congrats for making it this far! 😁

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Deployment

Finally, let’s create our nginx deployment that contains the mounted volume.

k apply -f nginx-deployment.yaml
apiVersion: apps/v1kind: Deploymentmetadata:  name: nginx-deployment  labels:    app: nginxspec:  replicas: 1  selector:    matchLabels:      app: nginx  template:    metadata:      labels:        app: nginx    spec:      containers:      - name: nginx        image: nginx:1.14.2        ports:        - containerPort: 80        volumeMounts:          - mountPath: "/data"            name: data-volume      volumes:        - name: "data-volume"          persistentVolumeClaim:            claimName: nuculabs-persistent-volume-claim

We mount the volume to the nginx container with:

        volumeMounts:          - mountPath: "/data"            name: data-volume

Then we add volumes to the spec and map “data-volume” to our PVC:

      volumes:        - name: "data-volume"          persistentVolumeClaim:            claimName: nuculabs-persistent-volume-claim

That’s it! 🎉

If you want to verify that the volume is mounted correctly you can SSH into the nginx pod and navigate to the /data directory.

Thanks for reading! 📚