nixos/systemd: add defaultPath option

nixos/lib/systemd-lib.nix

@@ -58,7 +58,6 @@ let
 
   cfg = config.systemd;
   lndir = "${pkgs.buildPackages.lndir}/bin/lndir";
-  systemd = cfg.package;
 in
 rec {
 
@@ -697,14 +696,7 @@ rec {
     { config, ... }:
     {
       imports = [ serviceConfig ];
-      # Default path for systemd services. Should be quite minimal.
-      config.path = mkIf config.enableDefaultPath (mkAfter [
-        pkgs.coreutils
-        pkgs.findutils
-        pkgs.gnugrep
-        pkgs.gnused
-        systemd
-      ]);
+      config.path = mkIf config.enableDefaultPath (mkAfter cfg.defaultPath);
     };
 
   stage1ServiceConfig = serviceConfig;

nixos/lib/systemd-unit-options.nix

@@ -379,7 +379,7 @@ rec {
           default = true;
           type = types.bool;
           description = ''
-            Whether to append a minimal default {env}`PATH` environment variable to the service, containing common system utilities.
+            Whether to append {option}`systemd.defaultPath` to the service's {env}`PATH` environment variable.
           '';
         };
 

nixos/modules/system/boot/systemd.nix

@@ -425,6 +425,17 @@ in
       '';
     };
 
+    defaultPath = mkOption {
+      type = types.listOf types.package;
+      default = [ ];
+      description = ''
+        Packages appended to the {env}`PATH` environment variable of all
+        system and user services.
+
+        Individual services can opt out by setting `enableDefaultPath = false`.
+      '';
+    };
+
     globalEnvironment = mkOption {
       type =
         with types;
@@ -733,6 +744,15 @@ in
       // listToAttrs (map (withName mountToUnit) cfg.mounts)
       // listToAttrs (map (withName automountToUnit) cfg.automounts);
 
+    # Default path for systemd services. Should be quite minimal.
+    systemd.defaultPath = [
+      pkgs.coreutils
+      pkgs.findutils
+      pkgs.gnugrep
+      pkgs.gnused
+      cfg.package
+    ];
+
     # Environment of PID 1
     systemd.managerEnvironment = {
       # Doesn't contain systemd itself - everything works so it seems to use the compiled-in value for its tools