feat(kubevirt-youko): serve VM golden images from a shared NFS store (#282)

* feat(kubevirt-youko): export a shared golden-image store over NFS

* feat(vm-images): upload golden images into the cluster

Replace the rsync-to-orangepi5 step with a CDI upload into the golden-image
PVCs (vms/golden-images in k8s-gitops), so VM images no longer depend on the
single-board file server.

hosts/k8s/kubevirt-youko/nfs-golden.nix

@@ -0,0 +1,31 @@
+{
+  ...
+}:
+let
+  # Shared golden-image store for the KubeVirt cluster. It is exported over
+  # NFSv4 so the cluster's NFS CSI driver can hand out RWX volumes to every
+  # node, and VM disks are cloned from it into local-path.
+  #
+  # It lives on the encrypted btrfs pool (/persistent), which has plenty of
+  # free space on this host.
+  goldenDir = "/persistent/nfs/golden";
+
+  # Only the homelab LAN may mount the export. The KubeVirt nodes are the
+  # clients (the CSI node plugin mounts from the node, not from the pod).
+  clientCidr = "192.168.5.0/24";
+in
+{
+  # Make sure the export directory exists before the NFS server starts.
+  systemd.tmpfiles.rules = [
+    "d ${goldenDir} 0755 root root -"
+  ];
+
+  services.nfs.server.enable = true;
+  services.nfs.server.exports = ''
+    ${goldenDir} ${clientCidr}(rw,sync,no_subtree_check,fsid=0,no_root_squash)
+  '';
+
+  # NFSv4 only needs 2049/tcp (no rpcbind/mountd/statd), so the firewall stays
+  # minimal. The export itself is already restricted to the LAN CIDR above.
+  networking.firewall.allowedTCPPorts = [ 2049 ];
+}

utils.nu

@@ -89,6 +89,14 @@ export def upload-vm [
         nix build $target
     }
 
-    let remote = $"root@192.168.5.178:/data/caddy/fileserver/vms/kubevirt-($name).qcow2"
-    rsync -avz --progress --copy-links --checksum result/nixos-image-*.qcow2 $remote
+    # Push the freshly built image into its golden-image PVC. The PVC is
+    # declared in k8s-gitops (vms/golden-images) and lives on the shared NFS
+    # store exported by kubevirt-youko, so every node can clone it when a VM
+    # is (re)created.
+    #
+    # Requires the CDI upload proxy to be reachable from here; it is exposed
+    # as a NodePort by the cluster (see infra/configs/base/kubevirt).
+    let uploadProxyUrl = "https://192.168.5.181:30443"
+    let image = (glob result/nixos-image-*.qcow2 | first)
+    virtctl image-upload pvc $"golden-($name)" -n vms --image-path $image --uploadproxy-url $uploadProxyUrl --insecure
 }