Restrict Kubernetes volume to a single pod

Question

I have a Kubernetes deployment for a Scylla database with a volume attached. It has one replica, with the manifest similar to the following:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: scylla
  labels:
    app: myapp
    role: scylla
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
      role: scylla
  template:
    metadata:
      labels:
        app: myapp
        role: scylla
    spec:
      containers:
        - name: scylla
          image: scylladb/scylla
          imagePullPolicy: Always
          volumeMounts:
            - mountPath: /var/lib/scylla/data
              name: scylladb
      volumes:
        - name: scylladb
          hostPath:
            path: /var/myapp/scylla/
            type: DirectoryOrCreate

When I perform an update, it will terminate the old pod and start a new pod before the old pod has stopped. This causes the database on the new pod to fail because it can't access the database files stored in the volume (because the old pod is still using it). How can I make it so that only one pod uses the volume at a time? (Short downtime is okay)

Answer 1

You can use Recreate Strategy in Deployment to do that. This will kill all the existing Pods before new ones are created. Ref: Kubernetes doc. So their will be some downtime because of that.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: scylla
  labels:
    app: myapp
    role: scylla
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
      role: scylla
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: myapp
        role: scylla
    spec:
      containers:
        - name: scylla
          image: scylladb/scylla
          imagePullPolicy: Always
          volumeMounts:
            - mountPath: /var/lib/scylla/data
              name: scylladb
      volumes:
        - name: scylladb
          hostPath:
            path: /var/myapp/scylla/
            type: DirectoryOrCreate