Install yaml2nix.

nix/configuration/roles/nixdev/default.nix

@@ -0,0 +1,25 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  imports = [ ];
+
+  options.me = {
+    nixdev.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = "Whether we want to install nixdev.";
+    };
+  };
+
+  config = lib.mkIf config.me.nixdev.enable {
+    environment.systemPackages = with pkgs; [
+      yaml2nix
+    ];
+  };
+}