Extract configuration to own module

hosts/thrall/default.nix

@@ -7,17 +7,12 @@ let
   extIface = "ens3";
   ledgerVHost = "ledger.failco.de";
 in {
-  imports = [ # Include the results of the hardware scan.
+  imports = [
     ./hardware-configuration.nix
     ../../modules/upgrade-pg-cluster.nix
+    ../../modules/nix-config.nix
   ];
 
-  nix.package = pkgs.nixUnstable;
-  nix.extraOptions = ''
-    experimental-features = nix-command flakes repl-flake ca-derivations
-  '';
-  # nix.registry.nixpkgs.flake = nixpkgs;
-
   # Binary Cache for Haskell.nix
   nix.settings.trusted-public-keys =
     [ "hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=" ];

modules/common-system.nix

@@ -1,5 +1,6 @@
-{config, pkgs, inputs, ...}:
-{
+{ config, pkgs, inputs, ... }: {
+  imports = [ ./nix-config.nix ];
+
   i18n.defaultLocale = "en_US.UTF-8";
   time.timeZone = "Europe/Berlin";
 
@@ -21,25 +22,9 @@
   networking.firewall.enable = true;
 
   nix = {
-      gc = {
-        automatic = true;
-        dates = "weekly";
-        options = "--delete-older-than 30d";
-      };
-
     registry = {
       nixpkgs.flake = inputs.nixpkgs;
       nixpkgs-unstable.flake = inputs.nixpkgs-unstable;
     };
-
-      settings = {
-        auto-optimise-store = true;
-        experimental-features = [ "nix-command" "flakes" ];
-        warn-dirty = false;
-
-        # avoid unwanted garbage collection when using direnv
-        keep-outputs = true;
-        keep-derivations = true;
-      };
   };
 }

modules/nix-config.nix

@@ -0,0 +1,22 @@
+{ config, lib, pkgs, ... }:
+
+{
+  nix = {
+    package = pkgs.nixUnstable;
+    gc = {
+      automatic = true;
+      dates = "weekly";
+      options = "--delete-older-than 30d";
+    };
+
+    settings = {
+      auto-optimise-store = true;
+      experimental-features = [ "nix-command" "flakes" "repl-flake" ];
+      warn-dirty = false;
+
+      # avoid unwanted garbage collection when using direnv
+      keep-outputs = true;
+      keep-derivations = true;
+    };
+  };
+}