K
Q

PersistentVolume does not use local host path

10/28/2018

I want to (temporarily) use localhost bound directories to persist application state of SonarQube. Below I describe how I achieved this in a self-hosted Kubernetes (1.11.3) cluster.

The problem I encounter is that despite everything working Kubernetes does not use the host path to persist the data (/opt/sonarqube/postgresql). Upon docker inspect of the SonarQube containers it uses the binds below.

How can I use the host mounted path for the mounts?

        "Binds": [
            "/var/lib/kubelet/pods/49666f05-dad0-11e8-95cd-666c474c0e54/volume-subpaths/sonarqube-pv-postgresql/sonarqube/0:/opt/sonarqube/conf",
            "/var/lib/kubelet/pods/49666f05-dad0-11e8-95cd-666c474c0e54/volumes/kubernetes.io~configmap/startup:/tmp-script/:ro",
            "/var/lib/kubelet/pods/49666f05-dad0-11e8-95cd-666c474c0e54/volume-subpaths/sonarqube-pv-postgresql/sonarqube/2:/opt/sonarqube/data",
            "/var/lib/kubelet/pods/49666f05-dad0-11e8-95cd-666c474c0e54/volume-subpaths/sonarqube-pv-postgresql/sonarqube/3:/opt/sonarqube/extensions",
            "/var/lib/kubelet/pods/49666f05-dad0-11e8-95cd-666c474c0e54/volumes/kubernetes.io~secret/default-token-zrjdj:/var/run/secrets/kubernetes.io/serviceaccount:ro",
            "/var/lib/kubelet/pods/49666f05-dad0-11e8-95cd-666c474c0e54/etc-hosts:/etc/hosts",
            "/var/lib/kubelet/pods/49666f05-dad0-11e8-95cd-666c474c0e54/containers/sonarqube/95053a5c:/dev/termination-log"
        ]

Here is what I did to set up the application

I created a StorageClass to create PVs that mount local paths:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: local-storage-nowait
provisioner: kubernetes.io/no-provisioner

Then I created two PVs to be used with the SonarQube helm chart like this:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: sonarqube-pv-postgresql
  labels:
    type: local
spec:
  capacity:
    storage: 20Gi
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: local-storage
  hostPath:
    path: /opt/sonarqube/postgresql
    type: DirectoryOrCreate
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - myhost

I launched the SonarQube helm chart with this additional config to use the PVs I just created

image:
  tag: 7.1

persistence:
  enabled: true
  storageClass: local-storage
  accessMode: ReadWriteOnce
  size: 10Gi

postgresql:
  persistence:
    enabled: true
    storageClass: local-storage
    accessMode: ReadWriteOnce
    size: 10Gi
-- Hedge
kubernetes

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1 Answer

10/29/2018

If you see the docs here

  • HostPath (Single node testing only – local storage is not supported in any way and WILL NOT WORK in a multi-node cluster)

Hence, that's probably why you are seeing it in a different place. I tried it myself and my PVC remains in pending state. So you can either use local like this:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-pv
  labels:
    vol=myvolume
spec:
  capacity:
    storage: 100Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  storageClassName: local-storage
  local:
    path: /mnt/disks/ssd1
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - example-node

Then you have to create the corresponding PVC:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: myclaim
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 100Gi
  storageClassName: local-storage
  selector:
    matchLabels:
      vol: "myvolume"

Then in the pod spec:

apiVersion: v1
kind: Pod
metadata:
  name: test-pd
spec:
  containers:
  - image: k8s.gcr.io/test-webserver
    name: test-container
    volumeMounts:
    - mountPath: /test-pd
      name: test-volume
  volumes:
  - name: test-volume
    persistentVolumeClaim:
      claimName: myclaim

You can also use hostPath directly in the pod spec if you don't care about landing on any node and having different data in each node:

apiVersion: v1
kind: Pod
metadata:
  name: test-pd
spec:
  containers:
  - image: k8s.gcr.io/test-webserver
    name: test-container
    volumeMounts:
    - mountPath: /test-pd
      name: test-volume
  volumes:
  - name: test-volume
    hostPath:
      # directory location on host
      path: /data
      # this field is optional
      type: DirectoryOrCreate
-- Rico
Source: StackOverflow