PersistenVolumeClain creating just a mapping between your actual PersistentVolume and your pod.
Using "helm.sh/resource-policy": keep annotation for PV is not the best idea, because of that remark in a documentation:
The annotation "helm.sh/resource-policy": keep instructs Tiller to skip this resource during a helm delete operation. However, this resource becomes orphaned. Helm will no longer manage it in any way. This can lead to problems if using helm install --replace on a release that has already been deleted, but has kept resources.
If you will create a PV manually after you will delete your release, Helm will remove PVC, which will be marked as "Available" and on next deployment, it will reuse it. Actually, you don't need to keep your PVC in the cluster to keep your data. But, for making it always using the same PV, you need to use labels and selectors.
For keep and reuse volumes you can:
Create PersistenVolume with the label, as an example, for_app=my-app and set "Retain" policy for that volume like this:
apiVersion: v1
kind: PersistentVolume
metadata:
name: myappvolume
namespace: my-app
labels:
for_app: my-app
spec:
persistentVolumeReclaimPolicy: Retain
capacity:
storage: 5Gi
accessModes:
- ReadWriteOnce
Modify your PersistenVolumeClaim configuration in Helm. You need to add a selector for using only PersistenVolumes with a label for_app=my-app.
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: myappvolumeclaim
namespace: my-app
spec:
selector:
matchLabels:
for_app: my-app
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 5Gi
So, now your application will use the same volume each time when it started.
But, please keep in mind, you may need to use selectors for other apps in the same namespace for preventing using your PV by them.