include perlless profile in NixOS

conditionally include perlless module

relax perlless constraint

nix/installer.nix

@@ -1,4 +1,15 @@
-{ config, lib, pkgs, ... }: {
+{
+  config,
+  lib,
+  pkgs,
+  modulesPath,
+  ...
+}:
+let
+  # can be dropped after 23.11 is removed
+  hasPerlless = builtins.pathExists "${modulesPath}/profiles/perlless.nix";
+in
+{
   # more descriptive hostname than just "nixos"
   networking.hostName = lib.mkDefault "nixos-installer";
 
@@ -6,9 +17,9 @@
   system.stateVersion = config.system.nixos.version;
 
   # use latest kernel we can support to get more hardware support
-  boot.kernelPackages = lib.mkDefault (pkgs.zfs.override {
-    removeLinuxDRM = pkgs.hostPlatform.isAarch64;
-  }).latestCompatibleLinuxPackages;
+  boot.kernelPackages =
+    lib.mkDefault
+      (pkgs.zfs.override { removeLinuxDRM = pkgs.hostPlatform.isAarch64; }).latestCompatibleLinuxPackages;
   boot.zfs.removeLinuxDRM = lib.mkDefault pkgs.hostPlatform.isAarch64;
 
   documentation.enable = false;
@@ -22,6 +33,12 @@
 
   imports = [
     ./nix-settings.nix
+    # reduce closure size by removing perl
+  ] ++ lib.optionals hasPerlless [
+    "${modulesPath}/profiles/perlless.nix"
+    # We relax the perl check in perlless.nix as not all images are actually perlless
+    # and we also want to allow users to install perl if they need it.
+    { system.forbiddenDependenciesRegexes = lib.mkForce []; }
   ];
 
   # Don't add nixpkgs to the image to save space, for our intended use case we don't need it