How to provide host files to VMs?

SUSE Virtualization
1

I have some files on my Harvester host (or also outside, if needed) and I would like to pass them as input to my Harvester VMs. Note that I would like to have this files available to virt-laucher pod and not inside the VM (so I cannot use cloud-init or similar).

So far the only way I have managed to make this work is creating a configMap and manually editing the yaml file to attach it to the VM. BTW as I am using harvester-csi-provider, Harvester doesn’t like my edit and VM won’t be editable anymore via config. Is there any better approach to pass files as input to VMs pods?

2

This is a valid use case but touches on the boundary between Harvester’s HCI layer and KubeVirt’s internals. Here’s what the official docs and KubeVirt support:

The challenge:

Harvester manages VMs through KubeVirt. The virt-launcher pod runs the QEMU/KVM process, and attaching arbitrary host files to it requires modifying the VM spec to mount volumes into the pod. Harvester’s UI provides a limited set of volume types (disk images, container disks, etc.) and doesn’t expose raw ConfigMap/Secret volume mounts directly in its interface.

Supported approaches via KubeVirt (kubectl/YAML):

  1. ConfigMap volumes: As you found, you can add a ConfigMap as a volume in the VM spec. The ConfigMap data is mounted as files inside the virt-launcher pod (not inside the VM guest OS). This is the supported KubeVirt mechanism for injecting files into the pod. Example in the VM spec:

  2. yaml

  3. volumes:

    • name: my-config
    • configMap:
    • name: my-configmap

  5. And in the domain.devices.disks or directly as a volume reference depending on your use case.

  6. Secret volumes: Similar to ConfigMap, you can use Kubernetes Secrets to inject files.

The Harvester CSI conflict:

You mentioned that when using harvester-csi-provider, Harvester overwrites or rejects manual YAML edits. This is a known limitation — Harvester’s controller reconciles the VM spec and may overwrite certain fields. The workaround is to use annotations or to apply changes after the VM is stopped, before it starts.

Practical recommendation:

  • Edit the VM YAML directly using kubectl edit vm <name> -n <namespace> from the cluster kubeconfig.
    • Add your ConfigMap or Secret volume mount to the VM spec.
      • Stop and restart the VM to apply changes.
    • Note: The Harvester UI may not show or preserve these custom volume mounts after future edits via the UI.
  • Reference: Official Harvester docs > VM Management and KubeVirt documentation on volumes