anchor.diff:          '';
         };
   
  +      clusterPeers = mkOption {
  +        type = types.listOf types.str;
  +        default = [];
  +        description = ''
  +          Initial peers for HA cluster.
  +        '';
  +      };
  +
         extraFlags = mkOption {
           type = types.listOf types.str;
           default = [];
  
positive.code:     "--config.file /tmp/alert-manager-substituted.yaml"
      "--web.listen-address ${cfg.listenAddress}:${toString cfg.port}"
      "--log.level ${cfg.logLevel}"
      ] ++ (optional (cfg.webExternalUrl != null)
        "--web.external-url ${cfg.webExternalUrl}"
      ) ++ (optional (cfg.logFormat != null)
  
negative.code:         '';
          serviceConfig = {
            Restart  = "always";
            StateDirectory = "alertmanager";
            DynamicUser = true; # implies PrivateTmp
            EnvironmentFile = lib.mkIf (cfg.environmentFile != null) cfg.environmentFile;
            WorkingDirectory = "/tmp";
  