daemonix approach

files/scripts/install-nix.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+rpm_url="https://nix-community.github.io/nix-installers/nix/x86_64/nix-multi-user-2.24.10.rpm"
+
+install -d /usr/share/nix-store /var/lib/nix-store /var/cache/nix-store /nix
+
+dnf install -y "$rpm_url"
+
+# Move the pre-populated store out of /nix so it can serve as the immutable lowerdir.
+if compgen -G "/nix/*" >/dev/null; then
+  mv /nix/* /usr/share/nix-store/
+fi

files/system/etc/modules-load.d/overlay.conf

@@ -0,0 +1 @@
+overlay

files/system/usr/bin/mount-nix-overlay.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+mkdir -p /usr/share/nix-store /var/lib/nix-store /var/cache/nix-store /nix
+
+# Skip if already mounted to avoid errors on reload.
+if mountpoint -q /nix; then
+  exit 0
+fi
+
+mount -t overlay overlay \
+  -o lowerdir=/usr/share/nix-store,upperdir=/var/lib/nix-store,workdir=/var/cache/nix-store \
+  /nix

files/system/usr/bin/nix-toolbox-ensure

@@ -1,22 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-image_ref="${NIX_TOOLBOX_IMAGE:-ghcr.io/thrix/nix-toolbox:42}"
-container_name="${NIX_TOOLBOX_CONTAINER:-nix-toolbox-42}"
-
-if ! command -v toolbox >/dev/null 2>&1; then
-  echo "toolbox not installed; skipping nix-toolbox setup" >&2
-  exit 0
-fi
-
-if ! command -v podman >/dev/null 2>&1; then
-  echo "podman not installed; skipping nix-toolbox setup" >&2
-  exit 0
-fi
-
-if podman container exists "$container_name"; then
-  exit 0
-fi
-
-echo "Creating $container_name from $image_ref"
-distrobox create --name "$container_name" --image "$image_ref"

files/system/usr/lib/systemd/system/nix-overlay.service

@@ -0,0 +1,14 @@
+[Unit]
+Description=Mount OverlayFS for /nix
+DefaultDependencies=no
+After=local-fs.target
+Before=nix-daemon.service
+ConditionPathExists=/usr/bin/mount-nix-overlay.sh
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/mount-nix-overlay.sh
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target

files/system/usr/lib/systemd/user/nix-toolbox-create.service

@@ -1,14 +0,0 @@
-[Unit]
-Description=Ensure nix-toolbox container is available for this user
-After=network-online.target
-Wants=network-online.target
-
-[Service]
-Type=oneshot
-ExecStart=/usr/bin/nix-toolbox-ensure
-RemainAfterExit=yes
-Restart=on-failure
-RestartSec=10
-
-[Install]
-WantedBy=default.target

recipes/recipe.yml

@@ -18,10 +18,15 @@ modules:
       - source: system
         destination: / # copies files/system/* (* means everything inside it) into your image's root folder /
 
+  - type: script
+    scripts:
+      - files/scripts/install-nix.sh
+
   - type: systemd
-    user:
+    system:
       enabled:
-        - nix-toolbox-create.service
+        - nix-overlay.service
+        - nix-daemon.service
 
   - type: dnf
     install: