Helm Chart: How to map an existing PersistentVolume to a Neo4j pod

When using the official Neo4j Helm chart to deploy Neo4j into Kubernetes, it is possible to mount an existing Kubernetes PersistentVolume into a Neo4j pod. This is achieved using the additionalVolumes configuration.

The following example shows how this is achieved using Docker Desktop. This will need customising for specific cloud vendors. There are two example ymal manifests attached: one for creating the PV and PVC and, one to be used to install the Helm chart.

Given the following PersistentVolume and PersistentVolumeClaim

apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-neo4j-pv
  labels:
    type: local
spec:
  storageClassName: hostpath
  capacity:
    storage: 256Mi
  accessModes:
    - ReadWriteMany
  hostPath:
    path: /tmp
  persistentVolumeReclaimPolicy: Retain
---
#
# PersistentVolumeClaim
#
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-neo4j-pvc
spec:
  storageClassName: hostpath
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 256Mi

We can mount this into the container as follows

neo4j:
  resources:
    cpu: "1"
    memory: "2Gi"

  startupProbe:
    failureThreshold: 1000
    periodSeconds: 30
  password: "password"
  edition: "enterprise"
  acceptLicenseAgreement: "yes"

# only required because we are running in Docker Desktop
podSpec:
  podAntiAffinity: false

volumes:
  data:
    mode: defaultStorageClass
    defaultStorageClass:
      requests:
        storage: 2Gi

additionalVolumes:
  - name: test
    persistentVolumeClaim:
      claimName: "my-neo4j-pvc"
additionalVolumeMounts:
  - mountPath: "/mnt/additionalVolume"
    name: test

In the above, we see that the volume is mounted into the container's /mnt/additionalVolume folder. This is shown in the following terminal output from inside the container

neo4j@neo4j-0:~$ ls -l /mnt
total 0
drwxrwxrwt 1 root root 60 Oct 30 09:59 additionalVolume
neo4j@neo4j-0:~$