Why local persistent volumes not visible in EKS? - kubernetes

Question

In order to test if I can get self written software deployed in amazon using docker images,
I have a test eks cluster.
I have written a small test script that reads and writes a file to see if I understand how to deploy. I have successfully deployed it in minikube, using three replica's. The replica's all use a shared directory on my local file system, and in minikube that is mounted into the pods with a volume
The next step was to deploy that in the eks cluster. However, I cannot get it working in eks. The problem is that the pods don't see the contents of the mounted directory.
This does not completely surprise me, since in minikube I had to create a mount first to a local directory on the server. I have not done something similar on the eks server.
My question is what I should do to make this working (if possible at all).
I use this yaml file to create a pod in eks:
apiVersion: v1
kind: PersistentVolume
metadata:
name: "pv-volume"
spec:
storageClassName: local-storage
capacity:
storage: "1Gi"
accessModes:
- "ReadWriteOnce"
hostPath:
path: /data/k8s
type: DirectoryOrCreate
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: "pv-claim"
spec:
storageClassName: local-storage
accessModes:
- "ReadWriteOnce"
resources:
requests:
storage: "500M"
---
apiVersion: v1
kind: Pod
metadata:
name: ruudtest
spec:
containers:
- name: ruud
image: MYIMAGE
volumeMounts:
- name: cmount
mountPath: "/config"
volumes:
- name: cmount
persistentVolumeClaim:
claimName: pv-claim
So what I expect is that I have a local directory, /data/k8s, that is visible in the pods as path /config.
When I apply this yaml, I get a pod that gives an error message that makes clear the data in the /data/k8s directory is not visible to the pod.
Kubectl gives me this info after creation of the volume and claim
[rdgon#NL013-PPDAPP015 probeer]$ kubectl get pv,pvc
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/pv-volume 1Gi RWO Retain Available 15s
persistentvolume/pvc-156edfef-d272-4df6-ae16-09b12e1c2f03 1Gi RWO Delete Bound default/pv-claim gp2 9s
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/pv-claim Bound pvc-156edfef-d272-4df6-ae16-09b12e1c2f03 1Gi RWO gp2 15s
Which seems to indicate everything is OK. But it seems that the filesystem of the master node, on which I run the yaml file to create the volume, is not the location where the pods look when they access the /config dir.

Answer 1

On EKS, there's no storage class named 'local-storage' by default.
There is only a 'gp2' storage class, which is also used when you don't specify a storageClassName.
The 'gp2' storage class creates a dedicated EBS volume and attaches it your Kubernetes Node when required, so it doesn't use a local folder. You also don't need to create the pv manually, just the pvc:
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: "pv-claim"
spec:
storageClassName: gp2
accessModes:
- "ReadWriteOnce"
resources:
requests:
storage: "500M"
---
apiVersion: v1
kind: Pod
metadata:
name: ruudtest
spec:
containers:
- name: ruud
image: MYIMAGE
volumeMounts:
- name: cmount
mountPath: "/config"
volumes:
- name: cmount
persistentVolumeClaim:
claimName: pv-claim
If you want a folder on the Node itself, you can use a 'hostPath' volume, and you don't need a pv or pvc for that:
apiVersion: v1
kind: Pod
metadata:
name: ruudtest
spec:
containers:
- name: ruud
image: MYIMAGE
volumeMounts:
- name: cmount
mountPath: "/config"
volumes:
- name: cmount
hostPath:
path: /data/k8s
This is a bad idea, since the data will be lost if another node starts up, and your pod is moved to the new node.
If it's for configuration only, you can also use a configMap, and put the files directly in your kubernetes manifest files.
apiVersion: v1
kind: ConfigMap
metadata:
name: ruud-config
data:
ruud.properties: |
my ruud.properties file content...
---
apiVersion: v1
kind: Pod
metadata:
name: ruudtest
spec:
containers:
- name: ruud
image: MYIMAGE
volumeMounts:
- name: cmount
mountPath: "/config"
volumes:
- name: cmount
configMap:
name: ruud-config

Answer 2

Please check whether the pv got created and its "bound" to PVC by running below commands
kubectl get pv
kubectl get pvc
Which will give information whether the objects are created properly

Answer 3

The local path you refer to is not valid. Try:
apiVersion: v1
kind: Pod
metadata:
name: ruudtest
spec:
containers:
- name: ruud
image: MYIMAGE
volumeMounts:
- name: cmount
mountPath: /config
volumes:
- name: cmount
hostPath:
path: /data/k8s
type: DirectoryOrCreate # <-- You need this since the directory may not exist on the node.