add alias+datastream rollover, and auto rollover on index tpl change (#40)

fixes #37

cmd/datastream.go

@@ -37,6 +37,7 @@ func Datastream(conf *cfg.Config) *cli.Command {
 			DatastreamShow(conf),
 			DatastreamCreate(conf),
 			DatastreamDelete(conf),
+			DatastreamRollover(conf),
 		},
 	}
 }
@@ -138,3 +139,61 @@ func DatastreamDelete(conf *cfg.Config) *cli.Command {
 		},
 	}
 }
+
+func DatastreamRollover(conf *cfg.Config) *cli.Command {
+	return &cli.Command{
+		Name:      "rollover",
+		Aliases:   []string{"roll"},
+		Usage:     "roll over a data stream",
+		UsageText: "rollover <data stream>",
+
+		ShellComplete: func(ctx context.Context, cmd *cli.Command) {
+			complete(cmd, Cindex)
+		},
+
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name:        "wait",
+				Usage:       "wait for active shards",
+				Destination: &conf.Wait,
+				Aliases:     []string{"w"},
+			},
+			&cli.BoolFlag{
+				Name:        "dry-run",
+				Usage:       "checks conditions but does not perform a rollover",
+				Destination: &conf.Wait,
+				Aliases:     []string{"n"},
+			},
+			&cli.StringFlag{
+				Name:        "max-age",
+				Usage:       "roll over after max age (eg: 7d, 2m, 8h)",
+				Destination: &conf.MaxAge,
+			},
+			&cli.IntFlag{
+				Name:        "max-docs",
+				Usage:       "roll over after max docs",
+				Destination: &conf.MaxDocs,
+			},
+			&cli.IntFlag{
+				Name:        "max-primary-shard-size",
+				Usage:       "roll over when primary shard size reaches size",
+				Destination: &conf.MaxShardSize,
+			},
+			&cli.IntFlag{
+				Name:        "max-primary-shard-docs",
+				Usage:       "roll over after max docs in primary shard reached",
+				Destination: &conf.MaxShardDocs,
+			},
+		},
+
+		Action: func(ctx context.Context, cmd *cli.Command) error {
+			alias := cmd.Args().Get(0)
+
+			if alias == "" {
+				return errors.New("no data stream specified")
+			}
+
+			return es.DatastreamRollover(conf, alias)
+		},
+	}
+}