add -p -t -D flags to cluster settings ls (#10)

cmd/cluster.go

@@ -140,6 +140,27 @@ func ClusterSettingsList(conf *cfg.Config) *cli.Command {
 		Usage:   "show cluster settings",
 		Aliases: []string{"ls", "get"},
 
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name:        "persistent",
+				Usage:       "only show persistent setting[s] (default)",
+				Destination: &conf.Persistent,
+				Aliases:     []string{"p"},
+			},
+			&cli.BoolFlag{
+				Name:        "transient",
+				Usage:       "only show transient setting[s]",
+				Destination: &conf.Transient,
+				Aliases:     []string{"t"},
+			},
+			&cli.BoolFlag{
+				Name:        "default",
+				Usage:       "only show default setting[s]",
+				Destination: &conf.Default,
+				Aliases:     []string{"D"},
+			},
+		},
+
 		Action: func(ctx context.Context, cmd *cli.Command) error {
 			if err := es.ClusterSettingsList(conf); err != nil {
 				return err