I must say this is something that showcases NixOS very well.

This is all it takes to start a nginx server. Add this block and everything starts up perfectly first time, using proper systemd sandboxing, with a certificate provisioned, and with a systemd timer for autorenewing the cert. Delete the block, and it's like the server never existed, all of that gets torn down cleanly.

  services.nginx = {
    enable = true;
    virtualHosts = {
      "mydomain.com" = {
        enableACME = true;
        locations."/" = {
          extraConfig = ''; # Config goes here
        };
      };
    };
  }