flake: add formatter and format

flake.nix

@@ -1,46 +1,47 @@
 # This is a basic NixOS flake template for a live ISO image
 # that can be used to install NixOS on a system.
-# ISO can be built using 
+# ISO can be built using
 # `nix build .#nixosConfigurations.nixos-iso.config.system.build.isoImage` - Graphical ISO
 # `nix build .#nixosConfigurations.nixos-minimal.config.system.build.isoImage` - Minimal ISO
 # Make sure to enable flakes and nix-command on the host system, before building the ISO
 # Resulting image can be found in ./result/iso/ directory
-
 {
   description = "Unstable NixOS custom installation media";
   inputs = {
     nixpkgs.url = "nixpkgs/nixos-unstable";
     bcachefs-tools.url = "github:koverstreet/bcachefs-tools";
   };
-  outputs =
-    { self, nixpkgs, ... }@inputs:
-    let
-      system = "x86_64-linux"; # change arch here
+  outputs = {
+    self,
+    nixpkgs,
+    ...
+  } @ inputs: let
+    system = "x86_64-linux"; # change arch here
 
-      specialArgs = {
-        inherit system;
-        inherit inputs;
-      };
-    in
-    {
-      ## GRAPHICAL ISO ##
-      nixosConfigurations.nixos-iso = nixpkgs.lib.nixosSystem {
-        inherit system;
-        modules = [
-          "${nixpkgs}/nixos/modules/installer/cd-dvd/installation-cd-graphical-gnome.nix"
-          "${nixpkgs}/nixos/modules/installer/cd-dvd/channel.nix"
-          ./graphical-configuration.nix
-        ];
-        inherit specialArgs;
-      };
-      ## MINIMAL ISO ##
-      nixosConfigurations.nixos-minimal = nixpkgs.lib.nixosSystem {
-        inherit system;
-        modules = [
-          "${nixpkgs}/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix"
-          ./minimal-configuration.nix
-        ];
-        inherit specialArgs;
-      };
+    specialArgs = {
+      inherit system;
+      inherit inputs;
+    };
+  in {
+    formatter.${system} = nixpkgs.legacyPackages.${system}.alejandra;
+    ## GRAPHICAL ISO ##
+    nixosConfigurations.nixos-iso = nixpkgs.lib.nixosSystem {
+      inherit system;
+      modules = [
+        "${nixpkgs}/nixos/modules/installer/cd-dvd/installation-cd-graphical-gnome.nix"
+        "${nixpkgs}/nixos/modules/installer/cd-dvd/channel.nix"
+        ./graphical-configuration.nix
+      ];
+      inherit specialArgs;
     };
+    ## MINIMAL ISO ##
+    nixosConfigurations.nixos-minimal = nixpkgs.lib.nixosSystem {
+      inherit system;
+      modules = [
+        "${nixpkgs}/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix"
+        ./minimal-configuration.nix
+      ];
+      inherit specialArgs;
+    };
+  };
 }

graphical-configuration.nix

@@ -3,17 +3,14 @@
 # ISO can be built using `nix build .#nixosConfigurations.nixos-iso.config.system.build.isoImage`
 # Make sure to enable flakes and nix-command on the host system before building the ISO
 # Resulting image can be found in ./result/iso/ directory
-
 {
   config,
   lib,
   pkgs,
   system,
   inputs,
   ...
-}:
-
-{
+}: {
   nixpkgs.hostPlatform = lib.mkDefault system;
   nix.settings.experimental-features = [
     "nix-command"

minimal-configuration.nix

@@ -3,16 +3,13 @@
 # ISO can be built using `nix build .#nixosConfigurations.nixos-minimal.config.system.build.isoImage`
 # Make sure to enable flakes and nix-command on the host system before building the ISO
 # Resulting image can be found in ./result/iso/ directory
-
 {
   config,
   lib,
   pkgs,
   system,
   ...
-}:
-
-{
+}: {
   nixpkgs.hostPlatform = lib.mkDefault system;
   nix.settings.experimental-features = [
     "nix-command"