K
Q

Directory shows empty after hostpath mounting method in Kubernetes

8/18/2020

I am trying to mount a directory called rstudio which is residing in /mnt/rstudio. But when I try to mount using persistent volume, the directory is showing up but not the files inside rstudio. Here's my deployment file

<!-- language: yaml -->
apiVersion: apps/v1
kind: Deployment
metadata:
  name: rsp-deployment
spec:
  selector:
    matchLabels:
      app: rsp
  replicas: 1
  strategy: {}
  template:
    metadata:
      labels:
        app: rsp
    spec:
      nodeSelector:
        kubernetes.io/hostname: testserver.local
      volumes:
       - name: rsp-persistent-storage
         persistentVolumeClaim:
           claimName: pv-claim-rsp
      containers:
      - env:
        - name: RSP_LICENSE
          value: MY LICENSE
        image: rstudio/rstudio-server-pro:latest
        name: rstudio-server-pro
        ports:
        - containerPort: 8787
        - containerPort: 5559
        volumeMounts:
         - name: rsp-persistent-storage
           mountPath: /tmp/rstudio
        resources: {}
        securityContext:
          privileged: true
      restartPolicy: Always
status: {}

---
kind: Service
apiVersion: v1
metadata:
  name: rstudio-server-pro
spec:
  selector:
    app: rsp
  ports:
  - protocol: TCP
    name: "8787"
    port: 8787
    targetPort: 8787
  type: NodePort

And my pv and pvc files are as follows

<!-- language: yaml -->
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-volume-rsp
spec:
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/rstudio"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pv-claim-rsp
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: ""
  resources:
    requests:
      storage: 5Gi

Inside my /mnt/rstudio there are these much files.

[root@test-server rstudio]# ls
launcher.conf                      launcher-mounts          launcher.pub        rserver.conf  
launcher.kubernetes.conf           launcher-mounts_working  logging.conf        rsession.conf 
launcher.kubernetes.profiles.conf  launcher.pem             notifications.conf  r-versions

But after the pod is up and running, the directory is showing empty. Any idea why? Thanks in advance!

-- Siddharth
kubernetes
kubernetes-pvc

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2 Answers

8/18/2020

Does you PVC make use of the PV you created? Check it with

kubectl get pvc

Try adding a label to the pv and use a matchLabels selector to make sure the PVC actually consumes the PV you just created:

<!-- language: yaml -->
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-volume-rsp
  labels:
    name: pv-volume-rsp  # Added
spec:
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/rstudio"

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pv-claim-rsp
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: ""
  resources:
    requests:
      storage: 5Gi
  selector:
    matchLabels:
      name: pv-volume-rsp  # Added
-- Sam
Source: StackOverflow
8/18/2020

LGTM. I am getting files if I swap the image with nginx. I would check two things: 1. Permissions: Check what permissions the files have. You may have to update your permissions or UID to access the files. 2. Does rstudio image use that path? It may be processing that folder when it starts. Try mounting to a different path and see if you can see the files.

Also, make sure you are launching the pod on the node where the host path exists. I am assuming testserver.local and test-server are the same.

HTH

-- Faheem
Source: StackOverflow