Add git-auto-update.nix

git-auto-update.nix

@@ -0,0 +1,62 @@
+{ config, pkgs, ... }:
+
+{
+  ########################################
+  # NixOS Git Auto Update Script
+  ########################################
+
+  environment.etc."nixos-git-update.sh" = {
+    mode = "0700";
+    text = ''
+      #!/run/current-system/sw/bin/bash
+      set -e
+
+      export PATH="/run/current-system/sw/bin:/nix/var/nix/profiles/default/bin"
+      export NIX_PATH="nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
+
+      LOCAL_PATH="/var/lib/nixos-config"
+      REPO_URL="https://git.skarockoi.de/ska/nixos-production.git"
+
+      if [ ! -d "$LOCAL_PATH/.git" ]; then
+        mkdir -p "$LOCAL_PATH"
+        chmod 700 "$LOCAL_PATH"
+        git clone "$REPO_URL" "$LOCAL_PATH"
+        exit 0
+      fi
+
+      cd "$LOCAL_PATH"
+
+      git fetch origin
+      LOCAL_HEAD=$(git rev-parse HEAD)
+      REMOTE_HEAD=$(git rev-parse origin/main)
+
+      if [ "$LOCAL_HEAD" != "$REMOTE_HEAD" ]; then
+        git reset --hard origin/main
+        nixos-rebuild boot -I nixos-config="$LOCAL_PATH/configuration.nix"
+      fi
+    '';
+  };
+
+  systemd.services.nixos-git-update = {
+    description = "Update NixOS from Git configuration";
+    script = "/etc/nixos-git-update.sh";
+    serviceConfig = {
+      Type = "oneshot";
+      User = "root";
+      Group = "root";
+      TimeoutStartSec = "10min";
+      Restart = "on-failure";
+      StandardOutput = "journal";
+      StandardError = "journal";
+    };
+  };
+
+  systemd.timers.nixos-git-update = {
+    description = "Periodic NixOS Git configuration check";
+    wantedBy = [ "timers.target" ];
+    timerConfig = {
+      OnBootSec = "60s";
+      OnUnitActiveSec = "5min";
+    };
+  };
+}