I have a folder of TFRecords on a network that I want to expose to multiple pods. The folder has been exported via NFS.
I have tried creating a Persistent Volume, followed by a Persistent Volume Claim. However, that just creates a folder inside the NFS mount, which I don't want. Instead, I want to Pod to access the folder with the TFRecords.
I have listed the manifests for the PV and PVC.
apiVersion: v1
kind: PersistentVolume
metadata:
name: nfs-tfrecord-pv
spec:
capacity:
storage: 30Gi
accessModes:
- ReadWriteMany
persistentVolumeReclaimPolicy: Retain
nfs:
path: /media/veracrypt1/
server: 1.2.3.4
readOnly: false
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: nfs-tfrecord-pvc
namespace: default
spec:
accessModes:
- ReadWriteMany
storageClassName: nfs-tfrecord
resources:
requests:
storage: 1Gi
I figured it out. The issue was I was looking at the problem the wrong way. I didn't need any provisioning. Instead, what was need was to simply mount the NFS volume within the container:
kind: Pod
apiVersion: v1
metadata:
name: pod-using-nfs
spec:
containers:
- name: app
image: alpine
volumeMounts:
- name: data
mountPath: /mnt/data
command: ["/bin/sh"]
args: ["-c", "sleep 500000"]
volumes:
- name: data
nfs:
server: 1.2.3.4
path: /media/foo/DATA
Related
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.
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
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
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.
I have map windows folder into me linux machine with
mount -t cifs //AUTOCHECK/OneStopShopWebAPI -o user=someuser,password=Aa1234 /xml_shared
and the following command
df -hk
give me
//AUTOCHECK/OneStopShopWebAPI 83372028 58363852 25008176 71% /xml_shared
after that I create yaml file with
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-nfs-jenkins-slave
spec:
storageClassName: jenkins-slave-data
accessModes:
- ReadWriteMany
resources:
requests:
storage: 4Gi
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: pv-nfs-jenkins-slave
labels:
type: jenkins-slave-data2
spec:
storageClassName: jenkins-slave-data
capacity:
storage: 4Gi
accessModes:
- ReadWriteMany
nfs:
server: 192.168.100.109
path: "//AUTOCHECK/OneStopShopWebAPI/jenkins_slave_shared"
this seems to not work when I create new pod
apiVersion: v1
kind: Pod
metadata:
name: jenkins-slave
labels:
label: jenkins-slave
spec:
containers:
- name: node
image: node
command:
- cat
tty: true
volumeMounts:
- mountPath: /var/jenkins_slave_shared
name: jenkins-slave-vol
volumes:
- name: jenkins-slave-vol
persistentVolumeClaim:
claimName: pvc-nfs-jenkins-slave
do i need to change the nfs ? what is wrong with me logic?
The mounting of CIFS share under Linux machine is correct but you need to take different approach to mount CIFS volume under Kubernetes. Let me explain:
There are some differences between NFS and CIFS.
This site explained the whole process step by step: Github CIFS Kubernetes.
hi all quick question on host paths for persistent volumes
I created a PV and PVC here
apiVersion: v1
kind: PersistentVolume
metadata:
name: task-pv-volume
labels:
type: local
spec:
storageClassName: manual
capacity:
storage: 10Gi
accessModes:
- ReadWriteOnce
hostPath:
path: "/mnt/data"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: task-pv-claim
spec:
storageClassName: manual
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 3Gi
and I ran a sample pod
apiVersion: v1
kind: Pod
metadata:
name: task-pv-pod
spec:
volumes:
- name: task-pv-storage
persistentVolumeClaim:
claimName: task-pv-claim
containers:
- name: task-pv-container
image: nginx
ports:
- containerPort: 80
name: "http-server"
volumeMounts:
- mountPath: "/usr/share/nginx/html"
name: task-pv-storage
i exec the pod and created a file
root#task-pv-pod:/# cd /usr/share/nginx/html
root#task-pv-pod:/usr/share/nginx/html# ls
tst.txt
However, when I go back to my host and try to ls the file , its not appearing. Any idea why? My PV and PVC are correct as I can see that it has been bounded.
ubuntu#ip-172-31-24-21:/home$ cd /mnt/data
ubuntu#ip-172-31-24-21:/mnt/data$ ls -lrt
total 0
A persistent volume (PV) is a kubernetes resource which has its own lifecycle independent of the pod pv documentation. Using a PVC to consume from a PV makes it visible in some other tool. For example azure files, ELB, a server with NFS, etc. My point here is that there is no reason why the PV should exist in the node.
If you want your persistence to be saved in the node use the hostPath option for PVs. Check this link. Though this is not a good production practice.
First of all, you don't need to create a PV if you are creating a PVC. PVCs create PV, if you have the right storageClass.
Second, hostPath is one delicate PV in Kubernetes world. That's the only PV that doen't need to be created to be mounted in a Pod. So you could have not created neither PV nor PVC and a hostPath volume would work just fine.
To make a test, delete your PV and PVC, and create your Pod like this:
apiVersion: v1
kind: Pod
metadata:
name: nginx-volume
labels:
app: nginx
spec:
containers:
- image: nginx
name: nginx
securityContext:
privileged: true
ports:
- containerPort: 80
name: nginx-http
volumeMounts:
- name: nginx
mountPath: /root/nginx-volume # path in the pod
volumes:
- name: nginx
hostPath:
path: /var/test # path in the host machine
I know this is a confusing concept, but that's how it is.
Question: How can I use raw devices attached to the host within the pod as block device.
I tried using "hostPath" with type "BlockDevice"
volumes:
- my-data:
hostPath:
path: /dev/nvme1n2
type: BlockDevice
containers:
.....
volumeDevices:
- name: my-data
devicePath: /dev/sda
This configuration gives me the below error.
Invalid value: "my-data": can only use volume source type of PersistentVolumeClaim for block mode
Can I achieve this using PersistentVolume and PersistentVolumeClaim ? Can someone help me with an example config. Appreciate the help.
Support for Block devices in K8s allows user and admins to use PVs & PVCs for raw block devices to be mounted in Pods. Excerpts below show a small use-case.
Create a PV which refers the Raw device on host say /dev/xvdf.
kind: PersistentVolume
apiVersion: v1
metadata:
name: local-raw-pv
spec:
volumeMode: Block
capacity:
storage: 100Gi
local:
path: /dev/xvdf
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Delete
Create a PVC claiming the block device for applications
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: block-pvc
spec:
accessModes:
- ReadWriteOnce
volumeMode: Block
resources:
requests:
storage: 10Gi
Create pod with the above claim which will mount the host device /dev/xvdf inside pod at path /dev/xvda
apiVersion: v1
kind: Pod
metadata:
name: pod-with-block-volume
spec:
containers:
- name: some-container
image: ubuntu
command: ["/bin/sh", "-c"]
args: [ "tail -f /dev/null" ]
volumeDevices:
- name: data
devicePath: /dev/xvda
volumes:
- name: data
persistentVolumeClaim:
claimName: block-pvc
I am trying to create a NFS sidecar for Kubernetes. The goal is to be able to mount an NFS volume to an existing pod without affecting performance. At the same time, I want to be able to mount the same NFS volume onto another pod or server (read-only perhaps) in order to view the content there. Has anyone tried this? Do anyone have the procedure?
Rather than use a sidecar I would suggest using a PersistentVolume which uses the NFS driver and PersistentVolumeClaim. If you use the RWX/ReadWriteMany access mode, you'll be able to mount the share into multiple pods.
For examplen the pv:
kind: PersistentVolume
apiVersion: v1
metadata:
name: mypv
spec:
capacity:
storage: 2Gi
nfs:
server: my.nfs.server
path: /myshare
accessModes:
- ReadWriteMany
persistentVolumeReclaimPolicy: Recycle
the pvc:
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: myclaim
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 2Gi
and mounted in a pod:
apiVersion: v1
kind: Pod
metadata:
name: mypod
spec:
containers:
- name: myfrontend
image: nginx
volumeMounts:
- mountPath: "/var/www/html"
name: mypd
volumes:
- name: mypd
persistentVolumeClaim:
claimName: myclaim
Kubernetes Docs on Persistent Volumes