Use k8s hostPath volumes in Docker Desktop on WSL2

Kubernetes allows to easily mount volumes based on a path on the node. This can be useful in local development as tools like Docker Desktop make it convenient to spin up a Kubernetes cluster on your local machine.

apiVersion: apps/v1
kind: Deployment
spec:
  ...
  template:
    spec:
      containers:
          image: alpine:latest
          volumeMounts:
            - mountPath: /secrets
              name: secrets-volume
      volumes:
        - name: secrets-volume
          hostPath:
            path: ???

But when you are using Kubernetes with Docker Desktop on WSL2 on a Windows machine, the above can become tricky as many paths will not behave as expected.

After failing to mount regular paths - both inside and outside WSL2, I condensed a long google search into finding that paths under /mnt/wsl are available to be used when referenced as /run/desktop/mnt/host/wsl.

Consider the following example: We want to mount the file secret.env from a local WSL2 folder into a Kubernetes pod. To do so, we first create the file locally:

mkdir /mnt/wsl/secrets
echo "thisissecretdata" > /mnt/wsl/secrets/secret.env

We then mount this via the deployment.yaml:

...
    spec:
      containers:
          image: alpine:latest
          volumeMounts:
            - mountPath: /secrets
              name: secrets-volume
      volumes:
        - name: secrets-volume
          hostPath:
            path: /run/desktop/mnt/host/wsl/secrets

Now inside our pod, we can access the file at /secrets/secret.env and will get the data originally stored in /mnt/wsl/secrets/secret.env.