anchor.diff:  let
     mysqlenv-common      = pkgs.buildEnv { name = "mysql-path-env-common";      pathsToLink = [ "/bin" ]; paths = with pkgs; [ bash gawk gnutar inetutils which ]; };
     mysqlenv-rsync       = pkgs.buildEnv { name = "mysql-path-env-rsync";       pathsToLink = [ "/bin" ]; paths = with pkgs; [ lsof procps rsync stunnel ]; };
  +
  +  # Common user configuration
  +  users = { ... }:
  +  {
  +    users.users.testuser = {
  +      isSystemUser = true;
  +      group = "testusers";
  +    };
  +    users.groups.testusers = { };
  +  };
   
   in {
     name = "mariadb-galera-rsync";
  
positive.code:         firewall.allowedTCPPorts = [ 3306 4444 4567 4568 ];
          firewall.allowedUDPPorts = [ 4567 ];
        };
        users.users.testuser = { isSystemUser = true; };
        systemd.services.mysql = with pkgs; {
          path = [ mysqlenv-common mysqlenv-rsync ];
        };
  
negative.code:     galera_04 =
        { pkgs, ... }:
        {
        imports = [ users ];
        networking = {
          interfaces.eth1 = {
            ipv4.addresses = [
  