pull-update: use writeShellApplication instead

system/pull-update.nix

@@ -7,17 +7,19 @@
 let
   deploy-url = "https://nix-cache.sigkill.computer/deploy/${hostname}";
 
-  pull-update = pkgs.writeShellScript "pull-update" ''
-    set -uo pipefail
-    export PATH=${
-      pkgs.lib.makeBinPath [
+  pull-update = pkgs.writeShellApplication {
+    name = "pull-update";
+
+    runtimeInputs = with pkgs; [
       pkgs.curl
       pkgs.coreutils
       pkgs.nix
       pkgs.systemd
       pkgs.util-linux
-      ]
-    }
+    ];
+
+    text = ''
+      set -uo pipefail
 
       # wait for actual connectivity, not just networkd "up"
       for i in $(seq 1 30); do
@@ -51,6 +53,7 @@ let
       sleep 10
       systemctl reboot
     '';
+  };
 in
 {
   systemd.services.pull-update = {