Kubernetes volume types

0
votes

I have dirctory on K8 master server.

I have 20 pods (With Deployment replicas).

I want all pods read from master directory /path/in/master/infiles And write their output to same directory /path/in/master/outfiles, Which Volume type should I need to use at this case? I Want my files not deleted after pod die.

I trying to look at the following: https://kubernetes.io/docs/concepts/storage/volumes/ but still don't know what is the best options for my case.

Any suggestions?

1
kubernetes
If the key part of your application is reading and writing files, Kubernetes might not be the best technology choice. Imagine these pods run on 8 different nodes; how do the files get to and from the nodes? – David Maze

1 Answers

4
votes

You can use hostPath volume.

A hostPath volume mounts a file or directory from the host node’s filesystem into your Pod.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: task-pv-volume
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteMany
  hostPath:
    path: "/path/in/master/infiles"

Check this guide on how to use hostPath.

A better option would be to use local volume.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-pv
spec:
  capacity:
    storage: 100Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  storageClassName: local-storage
  local:
    path: "/path/in/master/infiles"
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - example-node

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.

Edit:

The problem with storing data in the filesystem of the nodes itself is that there is no way to sync the data between the nodes. If this is needed for the application then using a PV backed by NFS in ReadWriteMany(RWX) mode is a better option. Here is guide on how to make this work in digital ocean.