Migrate host mount path from /var/lib/nix-csi to /var/lib/nixkube

Update the default host mount path to use the new nixkube naming:
- kubenix/options.nix: Change default hostMountPath to /var/lib/nixkube
- src/constants.py: Update HOST_MOUNT_PATH default to /var/lib/nixkube
- kubenix/daemonset.nix: Add /host volume mount to initContainer
- liximage.nix: Update init-copy script to:
  - Always create /host/var/lib directory
  - Migrate legacy /host/var/lib/nix-csi to /host/var/lib/nixkube if present
  - Use /host/var/lib/nixkube as the nix store path
  - Store result in /host/var/lib/nixkube/nix/var/result

This enables seamless migration from the old path while ensuring the new
path is used for all future operations.

All 38 tests passing, pyright 0 errors.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: Lillecarl

kubenix/daemonset.nix

@@ -78,7 +78,7 @@ in
                     volumeMounts = lib.mkNamedList {
                       nix-store.mountPath = "/nix-volume";
                       nix-config.mountPath = "/etc/nix";
-
+                      host-root.mountPath = "/host";
                       ssh-config.mountPath = "/etc/ssh";
                       ssh-key.mountPath = "/etc/ssh-key";
                       ssh-dynauth.mountPath = "/etc/ssh-dynauth";

kubenix/options.nix

@@ -67,9 +67,9 @@ in
         pyproject.project.version;
     };
     hostMountPath = lib.mkOption {
-      description = "Where on the host to put nix-csi store, / is untested and not recommended";
+      description = "Where on the host to put nixkube store, / is untested and not recommended";
       type = lib.types.path;
-      default = "/var/lib/nix-csi";
+      default = "/var/lib/nixkube";
     };
     internalServiceName = lib.mkOption {
       description = ''

liximage.nix

@@ -45,6 +45,13 @@ rec {
             mkdir /tmp
             rsync --archive ${fakeNss}/ /
 
+            # Ensure target directory exists and migrate legacy path if present
+            mkdir -p /host/var/lib
+            if [ -d /host/var/lib/nix-csi ]; then
+              echo "Migrating /host/var/lib/nix-csi to /host/var/lib/nixkube"
+              mv /host/var/lib/nix-csi /host/var/lib/nixkube
+            fi
+
             # Check if we can SSH to nix-cache
             EXTRA_SUBSTITUTERS="local?trusted=true"
             if nix store ping --store ssh-ng://nix@nix-cache; then
@@ -56,8 +63,8 @@ rec {
                 --extra-substituters "$EXTRA_SUBSTITUTERS" \
                 --max-jobs auto \
                 --option sandbox false \
-                --store /nix-volume \
-                --out-link /nix-volume/nix/var/result \
+                --store /host/var/lib/nixkube \
+                --out-link /host/var/lib/nixkube/nix/var/result \
                 --fallback \
                 "''${!ARCH}"
           '';

pkgs/nixkube/src/constants.py

@@ -56,9 +56,9 @@
 NRI_PLUGIN_NAME = os.environ.get("NRI_PLUGIN_NAME", "nix-csi")
 NRI_PLUGIN_IDX = os.environ.get("NRI_PLUGIN_IDX", "00")
 
-# NRI host mount path for bind mounts (default: /var/lib/nix-csi)
+# NRI host mount path for bind mounts (default: /var/lib/nixkube)
 # Set via HOST_MOUNT_PATH environment variable from kubenix
-HOST_MOUNT_PATH = Path(os.environ.get("HOST_MOUNT_PATH", "/var/lib/nix-csi"))
+HOST_MOUNT_PATH = Path(os.environ.get("HOST_MOUNT_PATH", "/var/lib/nixkube"))
 
 # Statically linked chroot binary used to execute OCI hooks from HOST_MOUNT_PATH
 COREUTILS_STATIC = Path(os.environ.get("COREUTILS_STATIC", "coreutils"))