anchor.diff:      in checkedConfig yml;
   
     cmdlineArgs = cfg.extraFlags ++ [
  -    "--config.file ${alertmanagerYml}"
  +    "--config.file /tmp/alert-manager-substituted.yaml"
       "--web.listen-address ${cfg.listenAddress}:${toString cfg.port}"
       "--log.level ${cfg.logLevel}"
       ] ++ (optional (cfg.webExternalUrl != null)
  
positive.code:           Extra commandline options when launching the Alertmanager.
          '';
        };
      };
    };
  
  
negative.code:       systemd.services.alertmanager = {
          wantedBy = [ "multi-user.target" ];
          after    = [ "network.target" ];
          preStart = ''
             ${lib.getBin pkgs.envsubst}/bin/envsubst -o /tmp/alert-manager-substituted.yaml" \
                                                      -i ${alertmanagerYml}"
          '';
          serviceConfig = {
            Restart  = "always";
            DynamicUser = true; # implies PrivateTmp
            EnvironmentFile = lib.mkIf (cfg.environmentFile != null) cfg.environmentFile;
            WorkingDirectory = "/tmp";
            ExecStart = "${cfg.package}/bin/alertmanager" +
              optionalString (length cmdlineArgs != 0) (" \\\n  " +
  