Add allHosts script and formatting app

flake.nix

@@ -21,6 +21,7 @@
         inherit system;
         config.allowUnfree = true; # For vscode
       };
+      hosts = [ "speer" "hummelberg" ];
     in {
       checks.${system}.formatCheck = let pkgs = pkgsUnstable;
       in pkgs.runCommand "nixfmt-check" { } ''
@@ -33,7 +34,6 @@
       # Build with `nixos-rebuild --flake .#<hostname>` or
       # `nix build .#nixosConfigurations.<hostname>.config.system.build.toplevel
       nixosConfigurations = let
-        hosts = [ "speer" "hummelberg" ];
         home-manager-config = {
           home-manager = {
             useGlobalPkgs = true;
@@ -80,7 +80,13 @@
       };
       devShell.${system} = import ./shell.nix { pkgs = pkgsUnstable; };
 
-      apps.${system}.format = let
+      packages.${system}.defaultPackage.${system} = let
+        configs = map (host: self.nixosConfigurations.${host}.config.system.build.toplevel) hosts;
+      in pkgsUnstable.linkFarmFromDrvs "allHosts" configs;
+
+
+      apps.${system} = {
+        format = let
           pkgs = pkgsUnstable;
           formatter = pkgsUnstable.writeShellScriptBin "formatter" ''
             ${pkgs.findutils}/bin/find . -type f -name '*.nix' -exec ${pkgs.nixfmt}/bin/nixfmt {} +
@@ -90,4 +96,5 @@
           program = "${formatter}/bin/formatter";
         };
       };
+    };
 }