hosts/modules: put builder back in a separate file

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

hosts/default.nix

@@ -38,6 +38,7 @@ in
       system = "x86_64-linux";
       modules = [
         ./remilia
+        ./modules/x86builder.nix
         inputs.mailserver.nixosModules.mailserver
         { nixpkgs.pkgs = self.legacyPackages.${system}; }
       ]

hosts/modules/minimal.nix

@@ -39,16 +39,7 @@
     package = pkgs.nixUnstable;
     extraOptions = ''
       experimental-features = nix-command flakes
-      builders-use-substitutes = true
     '';
-    settings.trusted-users = [ "root" ];
+    settings.trusted-users = [ "root" "spark" ];
-    buildMachines = [{
-      hostName = "satori";
-      systems = [ "x86_64-linux" "aarch64-linux" ];
-      maxJobs = 4;
-      speedFactor = 2;
-      supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
-    }];
-    distributedBuilds = true;
   };
 }

hosts/modules/x86builder.nix

@@ -0,0 +1,16 @@
+{ config, ... }:
+{
+  nix = {
+    extraOptions = ''
+      builders-use-substitutes = true
+    '';
+    buildMachines = [{
+      hostName = "satori";
+      systems = [ "x86_64-linux" "aarch64-linux" ];
+      maxJobs = 4;
+      speedFactor = 2;
+      supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
+    }];
+    distributedBuilds = true;
+  };
+}