Nexus on k3s on restart does not persist Users and data - kubernetes

Question

I have installed on K3S raspberry pi cluster nexus with the following setups for kubernetes learning purposes. First I created a StatefulSet:
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: nexus
namespace: dev-ops
spec:
serviceName: "nexus"
replicas: 1
selector:
matchLabels:
app: nexus-server
template:
metadata:
labels:
app: nexus-server
spec:
containers:
- name: nexus
image: klo2k/nexus3:latest
env:
- name: MAX_HEAP
value: "800m"
- name: MIN_HEAP
value: "300m"
resources:
limits:
memory: "4Gi"
cpu: "1000m"
requests:
memory: "2Gi"
cpu: "500m"
ports:
- containerPort: 8081
volumeMounts:
- name: nexusstorage
mountPath: /sonatype-work
volumes:
- name: nexusstorage
persistentVolumeClaim:
claimName: nexusstorage
Storage class
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: nexusstorage
provisioner: driver.longhorn.io
allowVolumeExpansion: true
reclaimPolicy: Delete
volumeBindingMode: Immediate
parameters:
numberOfReplicas: "3"
staleReplicaTimeout: "30"
fsType: "ext4"
diskSelector: "ssd"
nodeSelector: "ssd"
pvc
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: nexusstorage
namespace: dev-ops
spec:
accessModes:
- ReadWriteOnce
storageClassName: nexusstorage
resources:
requests:
storage: 50Gi
Service
apiVersion: v1
kind: Service
metadata:
name: nexus-server
namespace: dev-ops
annotations:
prometheus.io/scrape: 'true'
prometheus.io/path: /
prometheus.io/port: '8081'
spec:
selector:
app: nexus-server
type: LoadBalancer
ports:
- port: 8081
targetPort: 8081
nodePort: 32000
this setup will spin up nexus, but if I restart the pod the data will not persist and I have to create all the setups and users from scratch.
What I'm missing in this case?
UPDATE
I got it working, nexus needs on mount permissions on directory. The working StatefulSet looks as it follow
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: nexus
namespace: dev-ops
spec:
serviceName: "nexus"
replicas: 1
selector:
matchLabels:
app: nexus-server
template:
metadata:
labels:
app: nexus-server
spec:
securityContext:
runAsUser: 200
runAsGroup: 200
fsGroup: 200
containers:
- name: nexus
image: klo2k/nexus3:latest
env:
- name: MAX_HEAP
value: "800m"
- name: MIN_HEAP
value: "300m"
resources:
limits:
memory: "4Gi"
cpu: "1000m"
requests:
memory: "2Gi"
cpu: "500m"
ports:
- containerPort: 8081
volumeMounts:
- name: nexus-storage
mountPath: /nexus-data
volumes:
- name: nexus-storage
persistentVolumeClaim:
claimName: nexus-storage
important snippet to get it working
securityContext:
runAsUser: 200
runAsGroup: 200
fsGroup: 200

Answer 1

I'm not familiar with that image, although checking dockerhub, they mention using a Dockerfile similar to that of Sonatype. Then, I would change the mountpoint for your volume, to /nexus-data
This is the default path storing data (they set this env var, then declare a VOLUME). Which we can confirm, looking at the repository that most likely produced your arm-capable image
And following up on your last comment, let's try to also mount it in /opt/sonatype/sonatype-work/nexus3...
In your statefulset, change volumeMounts, to this:
volumeMounts:
- name: nexusstorage
mountPath: /nexus-data
- name: nexusstorage
mountPath: /opt/sonatype/sonatype-work/nexus3
volumes:
- name: nexusstorage
persistentVolumeClaim:
claimName: nexusstorage
Although the second volumeMount entry should not be necessary, as far as I understand. Maybe something's wrong with your storage provider?
Are you sure your PVC is write-able? Reverting back to your initial configuration, enter your pod (kubectl exec -it) and try to write a file at the root of your PVC.