Kubernetes: how to set VolumeMount user group and file permissions

Question

I'm running a Kubernetes cluster on AWS using kops. I've mounted an EBS volume onto a container and it is visible from my application but it's read only because my application does not run as root. How can I mount a PersistentVolumeClaim as a user other than root? The VolumeMount does not seem to have any options to control the user, group or file permissions of the mounted path.

Here is my Deployment yaml file:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: notebook-1
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: notebook-1
    spec:
      volumes:
      - name: notebook-1
        persistentVolumeClaim:
          claimName: notebook-1
      containers:
      - name: notebook-1
        image: jupyter/base-notebook
        ports:
        - containerPort: 8888
        volumeMounts:
        - mountPath: "/home/jovyan/work"
          name: notebook-1

Answer 1

The Pod Security Context supports setting an fsGroup, which allows you to set the group ID that owns the volume, and thus who can write to it. The example in the docs:

apiVersion: v1
kind: Pod
metadata:
  name: hello-world
spec:
  containers:
  # specification of the pod's containers
  # ...
  securityContext:
    fsGroup: 1234

More info on this is here