Kubernetes Persistent Volumes

How to tap into Kubernetes persistent volumes for your Orka environment.

For security reasons, Orka does not let you configure persistent volumes yourself. The MacStadium team needs to do that for you. However, when a persistent volume is configured for your environment, you can create persistent volume claims and deploy pods that consume the respective persistent volume.

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Quick command summary

brew install kubectl
orka kube [create / get] --account NAME -y
export KUBECONFIG=$(PWD)/kubeconfig-orka
kubectl config view
kubectl apply -f *.yaml --namespace=sandbox
kubectl get [pods / pvc]
kubectl describe
kubectl delete

Limitations

Persistent volumes are not applicable to standard Orka VMs. They can be consumed only by pods deployed with kubectl, and are called by functions such as attach-disk.

If you want to persist the storage of a standard Orka VM, use the image commit or save operations. For more information, see Orka Documentation: Create or update an image from a deployed VM.

Step 1: Request a persistent volume

Contact the MacStadium team and request a persistent volume (PV) for your Orka environment. Work closely with the team to help them create a PV that matches your requirements.

Step 2: Get Kubernetes-ready

You need to install kubectl and create a kube account for your Orka environment.

  1. If not already installed, install kubectl locally. For example:
brew install kubectl
  1. Create a kube account and export the kubeconfig. Alternatively, if you already have a kube account, get the respective kubeconfig and export it.
orka kube create --account <NAME> -y

OR

orka kube get --account <NAME> -y
  1. Export the resulting kubeconfig and verify that kubectl is configured properly.
export KUBECONFIG=$(pwd)/kubeconfig-orka

kubectl config view

If configured properly, you will see a similar output:

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: https://10.10.10.99:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    namespace: sandbox
    user: mykubeuser
  name: [email protected]
current-context: [email protected]
kind: Config
preferences: {}
users:
- name: mykubeuser
  user:
    token: eyJhbGciOiJSUz...

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Kubeconfig lost?

Sometimes, after a system or a terminal restart, you might need to re-get and re-export the kubeconfig for your account. Run orka kube get --account NAME -y followed by export KUBECONFIG=$(pwd)/kubeconfig-orka.

Step 3: Create the persistent volume claim

A persistent volume claim (PVC) lets you tap into your persistent volume and consume it. You need to create a basic yaml manifest for the PVC and apply it to the environment.

  1. Create the PVC manifest. For more information, see Kubernetes Documentation: PersistentVolumeClaims. For example:
# pvc.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: mypvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi

The values for metadata:name and metadata:namespace must match the values for claimRef:name and claimRef:namespace declared in the manifest of the persistent volume. Double-check with the MacStadium team for these values.

  1. Apply the PVC. Replace pvc.yaml with the complete file path to your own PVC manifest.
kubectl apply -f pvc.yaml --namespace=sandbox
  1. Verify that the persistent volume claim is bound to the persistent volume.
kubectl get pvc

If the persistent volume claim works as expected, you will see a similar output:

NAME      STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mypvc     Bound    my-pv      20Gi       RWO                           13s

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Status Pending?

If the status is Pending instead of Bound, double-check your PVC manifest, fix any naming issues, remove the old pvc with kubectl delete pvc NAME, and re-apply the fixed manifest. If the problem persists, contact the MacStadium team.

Step 4: Deploy a pod that uses the persistent volume

Now that you have created a PVC and bound it to the PV, you can deploy a pod that uses the PV. Create a pod manifest and apply it.

  1. Create the pod manifest. The pod needs to reference both the PV and the PVC. For example:
apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  volumes:
    - name: my-pv
      persistentVolumeClaim:
        claimName: mypvc
  containers:
    - name: mypod
      image: ubuntu
      command: ["/bin/bash", "-ec", "while :; do echo '.'; sleep 5 ; done"]
      volumeMounts:
        - mountPath: "/usr/share/mypod"
          name: my-pv
      restartPolicy: Never

This example deploys a Linux VM. Pay attention to the command line. Without it, the state of your Linux VM will become Stopped.

  1. Apply the pod. Replace mypod.yaml with the complete file path to your pod manifest.
kubectl apply -f mypod.yaml --namespace=sandbox
  1. Verify that the pod is deployed and running.
kubectl get pods

If the pod works as expected, you will see a similar output:

NAME          READY   STATUS    RESTARTS   AGE
pod/mypod     1/1     Running   0          12s
  1. Verify that the pod uses the claim and the persistent volume. Look for the data listed for Volumes.
kubectl describe pod <NAME>

(Optional) Step 5: Deploy a service to handle the networking between your pods and your Orka VMs

If you want to have connectivity between your Orka VMs and any pods deployed with kubectl, you need to deploy a networking service. For more information, see Kubernetes Documentation: Service.

Make sure to use the networking information provided your Orka IP Plan when assigning IPs.

What's next: Delete the PVC and release the PV

When you no longer need to use a PVC and the respective PV, you can delete the PVC to release the PV.

  1. Delete the PVC.
kubectl delete pvc <NAME>
  1. Contact the MacStadium team.
    • If you want to reclaim the storage, an administrator might need to clean it up and verify that it's available for use again. This would depend on the provisioning type and the reclaim policy for the PV.
    • If you no longer need the storage, an administrator can remove the PV.

Updated 3 months ago


Kubernetes Persistent Volumes


How to tap into Kubernetes persistent volumes for your Orka environment.

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