Ah, I get it, you're hitting a common gotcha with Docker Desktop's Kubernetes setup—it's not a "regular" single-node cluster running directly on your host OS, but instead the Kubernetes nodes are actually Docker containers themselves. That's why your mkdir commands are failing. Let me break down what's happening and how to fix it:

Why the commands fail #

• sudo: command not found: The Kubernetes node container (named docker-desktop) runs as the root user by default, so you don't need sudo at all. But even better, you shouldn't be trying to modify the node container's filesystem directly anyway.
• Read-only filesystem error: The root filesystem of the Docker Desktop Kubernetes node is mounted read-only for stability. Only specific directories (like /tmp or /var/lib/docker) are writable, but any data there will be lost when the node container restarts—totally useless for persistent storage.

The correct approach: Use hostPath with your host machine's filesystem #

Since Docker Desktop maps parts of your host OS's filesystem into the Kubernetes node container, you should create your persistent directory on your actual host machine (not inside the node container), then reference that path in your PersistentVolume (PV) config.

Here's how to do it step-by-step:

1. Create the data directory on your host

   • Mac/Linux: Open your terminal and run:

     mkdir -p ~/k8s-persistent-data
     

     Make sure this directory is in a location Docker Desktop is allowed to access (by default, /Users on Mac, /home on Linux are permitted).
   • Windows: Open Command Prompt or PowerShell and run:

     mkdir %USERPROFILE%\k8s-persistent-data
     

     This creates the folder in your C:\Users\<your-username> directory, which Docker Desktop is pre-configured to access.

2. Verify Docker Desktop has access to the directory

   • Open Docker Desktop settings:
     • Mac: Go to Resources > File Sharing and ensure /Users is checked.
     • Windows: Go to Resources > File Sharing and ensure C:\Users is checked.
   • If you created the directory outside these default paths, add it to the allowed list and restart Docker Desktop.

3. Create your PersistentVolume (PV) and PersistentVolumeClaim (PVC)
   Create a file named pv.yaml with the following content—replace the path value with the correct mapped path for your OS:

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: task-pv-volume
     labels:
       type: local
   spec:
     storageClassName: manual
     capacity:
       storage: 10Gi
     accessModes:
       - ReadWriteOnce
     hostPath:
       # Mac: /host_mnt/Users/<your-username>/k8s-persistent-data
       # Windows: /run/desktop/mnt/host/c/Users/<your-username>/k8s-persistent-data
       # Linux: /home/<your-username>/k8s-persistent-data
       path: "/host_mnt/Users/john/k8s-persistent-data"
   

   Then create a pvc.yaml file:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: task-pv-claim
   spec:
     storageClassName: manual
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 3Gi
   

4. Apply the configurations
   Run these commands in your terminal:

   kubectl apply -f pv.yaml
   kubectl apply -f pvc.yaml
   

5. Mount the PVC in your Pod
   When defining your Pod, reference the PVC to mount the persistent storage:

   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
   

Key Notes #

• Any data saved to the mounted path in the Pod will be stored in your host machine's directory, so it survives Kubernetes node restarts or Docker Desktop reboots.
• Avoid modifying the Kubernetes node container's filesystem directly—it's not designed for persistent storage, and changes will be lost.

内容的提问来源于stack exchange，提问作者Snowcrash