How to specify an existing Persistent Volume with loki-stack Helm Chart

Hi,

I am trying to get Loki and Grafana in loki-stack (helm-charts/charts/loki-stack at main · grafana/helm-charts · GitHub) to use an existing Persistent Volume that is hostPath based, instead of the automatically provisioned ones when persistence is activated.

I looked at the values.yaml of loki for reference: loki/values.yaml at main · grafana/loki · GitHub

persistence:
  enabled: false
  accessModes:
  - ReadWriteOnce
  size: 10Gi
  annotations: {}
  # selector:
  #   matchLabels:
  #     app.kubernetes.io/name: loki
  # subPath: ""
  # existingClaim:

Specifying a PVC in existingClaim did not work, and I could not find any documentation on this. How can I change the values.yaml to use a specific Persistent Volume?

Thanks for your feedback!