Only bind mysql to the localhost address

That way its not addressable from outside.

anythingforafriend/etc/nixos/configuration.nix

@@ -70,6 +70,7 @@
   services.mysql = {
     enable = true;
     package = pkgs.mariadb;
+    settings.mysqld.bind-address = "127.0.0.1";
   };
   services.nginx = {
     enable = true;