How to mount local volume to ksonnet component deployed in kubeflow

Question

I am trying to mount a local directory into a component deployed in kubeflow using ksonnet prototype.

Answer 1

There is no way to mount a local directory into a Kubernetes pod (after all kubeflow and ksonnet just create pods and other Kubernetes resources).

If you want your files to be available in Kubernetes I can think in two options:

1. Create a custom docker image, copying the folder you want, and push it to a registry. Kubeflow has parameters to customize the images to be deployed.

2. Use NFS. That way you could mount the NFS volume in your local and also in the pods. To do that you should modify the ksonnet code, since in the last stable version it is not implemented.

If you provide more information about what component are you trying to deploy and which cloud provider you're using, I could help you more

Answer 2

If by local directory you mean local directory on the node, then it is possible to mount a directory on the node’s filesystem inside a pod using HostPath or Local Volumes feature.

A hostPath volume mounts a file or directory from the host node’s filesystem into your Pod. This is not something that most Pods will need, but it offers a powerful escape hatch for some applications.

A local volume represents a mounted local storage device such as a disk, partition or directory.

Local volumes can only be used as a statically created PersistentVolume. Dynamic provisioning is not supported yet.

Compared to hostPath volumes, local volumes can be used in a durable and portable manner without manually scheduling Pods to nodes, as the system is aware of the volume’s node constraints by looking at the node affinity on the PersistentVolume.

For example:

# HostPaht Volume example
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: Directory

# local volume example (beta in v1.10)
apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-pv
spec:
  capacity:
    storage: 100Gi
  # volumeMode field requires BlockVolume Alpha feature gate to be enabled.
  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

GlusterFS is also available as Volume or as Persistent Volume (Access modes:ReadWriteOnce,ReadOnlyMany,ReadWriteMany)

A glusterfs volume allows a Glusterfs (an open source networked filesystem) volume to be mounted into your Pod. Unlike emptyDir, which is erased when a Pod is removed, the contents of a glusterfs volume are preserved and the volume is merely unmounted. This means that a glusterfs volume can be pre-populated with data, and that data can be “handed off” between Pods. GlusterFS can be mounted by multiple writers simultaneously.

See the GlusterFS example for more details.