nix/modules/services/syncthing/default.nix

{
  username,
  domain,
  ...
}: {
  services.syncthing = {
    enable = true;
    dataDir = "/home/${username}";
    openDefaultPorts = true;
    configDir = "/home/${username}/.config/syncthing";
    user = username;
    group = "users";
    guiAddress = "0.0.0.0:8384";
  };
  services.nginx = {
    enable = true;
    recommendedProxySettings = true;
    recommendedTlsSettings = true;
    virtualHosts."sync.${domain}" = {
      enableACME = true;
      forceSSL = true;
      locations."/" = {
        proxyPass = "http://127.0.0.1:8384";
        proxyWebsockets = true;
        extraConfig =
          "proxy_ssl_server_name on;"
          + "proxy_pass_header Authorization;";
      };
    };
  };
}