anchor.diff:          firewall.allowedTCPPorts = [ 3306 4444 4567 4568 ];
           firewall.allowedUDPPorts = [ 4567 ];
         };
  -      users.users.testuser = { isSystemUser = true; };
         systemd.services.mysql = with pkgs; {
           path = [ mysqlenv-common mysqlenv-mariabackup ];
         };
  
positive.code: let
    mysqlenv-common      = pkgs.buildEnv { name = "mysql-path-env-common";      pathsToLink = [ "/bin" ]; paths = with pkgs; [ bash gawk gnutar inetutils which ]; };
    mysqlenv-mariabackup = pkgs.buildEnv { name = "mysql-path-env-mariabackup"; pathsToLink = [ "/bin" ]; paths = with pkgs; [ gzip iproute2 netcat procps pv socat ]; };
  
  in {
    name = "mariadb-galera-mariabackup";
  
negative.code:     galera_01 =
        { pkgs, ... }:
        {
        imports = [ users ];
        networking = {
          interfaces.eth1 = {
            ipv4.addresses = [
  