How to configure a Helm chart to a block storage volume

Posted on October 28, 2019

I want to deploy a Helm chart on my Kubernetes cluster, but I want the deployment attached to a block storage volume, mainly so data is protected from automatic upgrades. Is there any way to do this?

I tried reading the documentation but I do not understand how I can do this with Helm (kinda new to Kubernetes :/): https://www.digitalocean.com/docs/kubernetes/how-to/add-volumes/

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Bobby

May 17, 2023

Hi there,

When using Helm, you typically specify your desired configuration for the Kubernetes resources in a values.yaml file. To attach a block storage volume to a deployment, you would create a PVC in this file.

Here is a simplified example of how you might define a PVC in your values.yaml:

persistence:
  enabled: true
  storageClassName: do-block-storage
  accessModes:
    - ReadWriteOnce
  size: 10Gi

In this example, do-block-storage would be the name of the StorageClass that represents block storage volumes on DigitalOcean. The accessModes field defines how the volume can be accessed from a single node: ReadWriteOnce means the volume can be mounted as read-write by a single node.

Then, in your Helm chart’s templates, you would include a PVC and reference the values from values.yaml. Here’s an example of how that might look:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-claim
spec:
  storageClassName: {{ .Values.persistence.storageClassName }}
  accessModes:
    - {{ .Values.persistence.accessModes }}
  resources:
    requests:
      storage: {{ .Values.persistence.size }}

In your Deployment or Pod specification, you would then mount this PVC to your pods. Here’s a simplified example:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  template:
    spec:
      containers:
      - name: my-container
        image: my-image
        volumeMounts:
        - mountPath: /path/to/mount
          name: my-volume
      volumes:
      - name: my-volume
        persistentVolumeClaim:
          claimName: my-claim

In this example, the volume my-volume is backed by the PVC my-claim, and is mounted into the pod at /path/to/mount.

Please note that you need to replace the placeholders (my-claim, my-deployment, my-container, my-image, /path/to/mount, my-volume) with values that are appropriate for your use case.

Best,

Bobby