flake: add system agnostic devShell w/ flake-utils

flake.lock

@@ -1,5 +1,20 @@
 {
   "nodes": {
+    "futils": {
+      "locked": {
+        "lastModified": 1614513358,
+        "narHash": "sha256-LakhOx3S1dRjnh0b5Dg3mbZyH0ToC9I8Y2wKSkBaTzU=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5466c5bbece17adaab2d82fae80b46e807611bf3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "home-manager": {
       "inputs": {
         "nixpkgs": [
@@ -53,6 +68,7 @@
     },
     "root": {
       "inputs": {
+        "futils": "futils",
         "home-manager": "home-manager",
         "nixpkgs": "nixpkgs",
         "nur": "nur"

flake.nix

@@ -5,11 +5,13 @@
     home-manager.inputs.nixpkgs.follows = "nixpkgs";
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     nur.url = "github:nix-community/NUR";
+    futils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, nur, home-manager }:
+  outputs = { self, nixpkgs, nur, home-manager, futils }:
     let
       inherit (nixpkgs) lib;
+      inherit (futils.lib) eachDefaultSystem;
 
       defaultModules = [
         ({ pkgs, ... }: {
@@ -36,7 +38,20 @@
         ];
       };
     in
-    {
+    eachDefaultSystem
+      (system:
+        let
+          pkgs = nixpkgs.legacyPackages.${system};
+        in
+        {
+          devShell = pkgs.mkShell {
+            name = "NixOS-config";
+            buildInputs = with pkgs; [
+              gitAndTools.pre-commit
+              nixpkgs-fmt
+            ];
+          };
+        }) // {
       nixosConfigurations = nixpkgs.lib.mapAttrs buildHost {
         porthos = "x86_64-linux";
       };