Add optional system modules

hosts/default.nix

@@ -3,9 +3,12 @@
 in {
   vboxnix = lib.nixosSystem {
     system = "x86_64-linux";
-    modules = [ 
+    modules = [
-      ../system
       ./vbox_nix
+      ../system
+      ../system/options/systemd-boot.nix
+      ../system/options/cachix.nix
+      ../system/options/oomd.nix
       ../modules/services/ssh.nix
     ];
   };

hosts/vbox_nix/default.nix

@@ -1,11 +1,16 @@
-{lib, ...}:
+{ lib, pkgs, ...}:
 {
   imports = [ ./hardware-configuration.nix ];
 
-  boot.loader = {
+  nix.settings = {
-    systemd-boot.enable = true;
+    max-jobs = 6;
-    efi.canTouchEfiVariables = true;
+    cores = 6;
-    timeout = 3;
+  };
+
+  security.sudo.package = pkgs.sudo.override { withInsults = true; };
+  security.polkit.enable = true;
+  services = {
+    udisks2.enable = true;
   };
 
   networking.hostName = "vboxnix";

system/network.nix

@@ -9,5 +9,18 @@
     };
   };
 
-  services.resolved.enable = true;
+  services.resolved = {
+      enable = true;
+      fallbackDns = [
+          "9.9.9.9"
+          "2620:fe::fe"
+      ];
+  };
+
+  # don't wait for network to boot faster
+  # https://old.reddit.com/r/NixOS/comments/vdz86j/how_to_remove_boot_dependency_on_network_for_a
+  systemd = {
+      targets.network-online.wantedBy = lib.mkForce []; # default is [ "multi-user.target" ]
+      services.NetworkManager-wait-online.wantedBy = lib.mkForce []; # default is [ "network-online.target" ]
+  };
 }

system/options/cachix.nix

@@ -0,0 +1,14 @@
+_: {
+  nix.settings = {
+    substituters = [
+        "https://nix-community.cachix.org"
+        "https://nixpkgs-wayland.cachix.org"
+        "https://viperml.cachix.org"
+    ];
+    trusted-public-keys = [
+        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+        "nixpkgs-wayland.cachix.org-1:3lwxaILxMRkVhehr5StQprHdEo4IrE8sRho9R9HOLYA="
+        "viperml.cachix.org-1:qZhKBMTfmcLL+OG6fj/hzsMEedgKvZVFRRAhq7j8Vh8="
+    ];
+  };
+}

system/options/oomd.nix

@@ -0,0 +1,9 @@
+_: {
+    systemd.oomd = {
+        enable = true;
+        enableSystemSlice = true;
+        enableRootSlice = true;
+        enableUserSlices = true;
+    };
+}
+

system/options/systemd-boot.nix

@@ -0,0 +1,12 @@
+_: {
+    boot.loader = {
+        systemd-boot = {
+            enable = true;
+            memtest86.enable = true;
+            editor = true;
+        };
+        efi.canTouchEfiVariables = true;
+        timeout = 3;
+    };
+}
+