Kubernetes Persistent Volumes

Persistent Volumes in Kubernetes allow the operators to store data outside the Pods that will be persistent across updates or reboot. It also allows these Persistent Volumes to be mounted on multiple pods.
See the official Kubernetes documentation on Persistent Volumes for more information. 

Contents

Using Kubernetes Persistent Volumes

1. In order to use Persistent Volumes, you must declare a PersistentVolumeClaim in order to request some space.

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: example-pvc
   spec:
     storageClassName: cloudstack-custom
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 1Gi

   The only part which is special here is "cloudstack-custom" which is a pre-defined storage class declared by Leaseweb when we have provisioned your cluster.
   The other interesting part is the spec.resources.requests.storage which requests exactly 1 Gi for the volume, which allows choosing the specific size you desire for that volume.
   
   

2. Then, to use this PersistentVolume in a container, you can use the PersistentVolume's name to specify in your Pod, such as : 

   apiVersion: v1
   kind: Pod
   metadata:
     name: example-pod
   spec:
     containers:
       - name: example
         image: busybox
         volumeMounts:
           - mountPath: "/data"
             name: example-volume
         stdin: true
         stdinOnce: true
         tty: true
     volumes:
       - name: example-volume
         persistentVolumeClaim:
           claimName: example-pvc

3. Once you have applied both of these configurations using kubectl apply -f, a new pod will be added, and the volume will be mounted under /data.

Relevant documentation about Kubernetes Persistent Volumes