Use hostPath volumes

Volume mount modes

Example

• Use the following template to directly mount a hostPath volume to a pod:

  apiVersion: v1
  kind: Pod
  metadata:
    name: test
  spec:
    containers:
    - image: nginx:1.7.9
      name: test
      volumeMounts:
      - mountPath: /test
        name: test-volume
    volumes:
    - name: test-volume
      hostPath:
        path: /data
        type: DirectoryOrCreate

• You can also provision a hostPath volume as a persistent volume (PV) and create a persistent volume claim (PVC) that can be used to mount the PV to pods.

  apiVersion: v1
  kind: PersistentVolume
  metadata:
    name: task-pv-volume
    labels:
      type: local
  spec:
    capacity:
      storage: 10Gi
    accessModes:
      - ReadWriteOnce
    hostPath:
      path: "/data"
  ---
  apiVersion: v1
  kind: PersistentVolumeClaim
  metadata:
    name: hostpath
  spec:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 10Gi

• Mount hostPath volumes to running pods
  In Kubernetes, after a pod starts to run, you cannot change the PVs that are mounted to the pod. If you need to dynamically mount external volumes to the running pod, perform the following steps:

  Note

  • This method uses the mount propagation feature provided by Linux. You must specify the mountPropagation field as Bidirectional when you mount a hostPath volume to the target pod. This propagates a directory on the host node to containers in the pod.
  • The target pod must be running in privilege mode. This is required if you specify mountPropagation as Bidirectional.
  • The target pod must be mounted with a directory from the file system of the host node. This way, running containers in the pod can receive all subsequent mounts to this directory.
  Use the following template to create an NGINX application that uses a hostPath volume:

  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: deployment-nas
    labels:
      app: nginx
  spec:
    selector:
      matchLabels:
        app: nginx
    template:
      metadata:
        labels:
          app: nginx
      spec:
        containers:
        - name: nginx
          image: nginx:1.7.9
          command: ["sh", "-c"]
          args: ["sleep 10000"]
          securityContext:
            privileged: true
            capabilities:
              add: ["SYS_ADMIN"]
            allowPrivilegeEscalation: true
          volumeMounts:
            - name: dynamic-volume
              mountPropagation: "Bidirectional"
              mountPath: "/dynamic-volume"
        volumes:
          - name: dynamic-volume
            hostPath:
              path: /mnt/dynamic-volume
              type: DirectoryOrCreate

  Note

  • Directory on the host node: /mnt/dynamic-volume.
  • Mount path in the pod: /dynamic-volume.

  The preceding configuration propagates external mounts targeting the /mnt/dynamic-volume/**** directory on the host node to the pod that is mounted with a hostPath volume of the /mnt/dynamic-volume directory. This allows you to dynamically mount external volumes to running pods.