A new start

modules/darwin/nix/default.nix

@@ -0,0 +1,74 @@
+{ options
+, config
+, pkgs
+, lib
+, ...
+}:
+with lib;
+with lib.metacfg; let
+  cfg = config.metacfg.nix;
+in
+{
+  options.metacfg.nix = with types; {
+    enable = mkBoolOpt true "Whether or not to manage nix configuration.";
+    package = mkOpt package pkgs.nixUnstable "Which nix package to use.";
+  };
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = with pkgs; [
+      deploy-rs
+      nixfmt
+      nix-index
+      nix-prefetch-git
+    ];
+
+    nix =
+      let
+        users = [ "root" config.metacfg.user.name ];
+      in
+      {
+        package = cfg.package;
+
+        settings = {
+          experimental-features = "nix-command flakes";
+          http-connections = 50;
+          warn-dirty = false;
+          log-lines = 50;
+
+          # Large builds apparently fail due to an issue with darwin:
+          # https://github.com/NixOS/nix/issues/4119
+          sandbox = false;
+
+          # This appears to break on darwin
+          # https://github.com/NixOS/nix/issues/7273
+          auto-optimise-store = false;
+
+          allow-import-from-derivation = true;
+
+          trusted-users = users;
+          allowed-users = users;
+
+          # NOTE: This configuration is generated by nix-installer so I'm adding it here in
+          # case it becomes important.
+          extra-nix-path = "nixpkgs=flake:nixpkgs";
+          build-users-group = "nixbld";
+        };
+        #// (lib.optionalAttrs config.metacfg.tools.direnv.enable {
+        #  keep-outputs = true;
+        #  keep-derivations = true;
+        #});
+
+        gc = {
+          automatic = true;
+          interval = { Day = 7; };
+          options = "--delete-older-than 30d";
+          user = config.metacfg.user.name;
+        };
+
+        # flake-utils-plus
+        generateRegistryFromInputs = true;
+        generateNixPathFromInputs = true;
+        linkInputs = true;
+      };
+  };
+}