anchor.diff:        username = mkOption {
           type = types.str;
           default = "roundcube";
  -        description = "Username for the postgresql connection";
  +        description = ''
  +          Username for the postgresql connection.
  +          If <literal>database.host</literal> is set to <literal>localhost</literal>, a unix user and group of the same name will be created as well.
  +        '';
         };
         host = mkOption {
           type = types.str;
  
positive.code:       };
      };
  
      services.postgresql = mkIf (cfg.database.host == "localhost") {
        enable = true;
      };
  
      services.phpfpm.pools.roundcube = {
        user = "nginx";
        phpOptions = ''
          error_log = 'stderr'
          log_errors = on
  
negative.code:       };
        password = mkOption {
          type = types.str;
          description = "Password for the postgresql connection. Do not use: the password will be stored world readable in the store; use <literal>passwordFile</literal> instead.";
          default = "";
        };
        passwordFile = mkOption {
          type = types.str;
          description = "Password file for the postgresql connection. Must be readable by user <literal>nginx</literal>. Ignored if <literal>database.host</literal> is set to <literal>localhost</literal>, as peer authentication will be used.";
        };
        dbname = mkOption {
          type = types.str;
  