feat(cmd/inflxud): add support for writing to stdout in export-lp

CHANGELOG.md

@@ -31,6 +31,7 @@ or `/query` HTTP endpoints.
 1. [20971](https://github.com/influxdata/influxdb/pull/20971): Set a default `--http-idle-timeout` of 3m in `influxd`.
 1. [20861](https://github.com/influxdata/influxdb/pull/20861): Update Telegraf plugins in UI to include additions and changes in 1.18 release.
 1. [20894](https://github.com/influxdata/influxdb/pull/20894): Display task IDs in the UI.
+1. [21046](https://github.com/influxdata/influxdb/pull/21046): Write to standard out when `--output-path -` is passed to `influxd inspect export-lp`.
 
 ### Bug Fixes
 

cmd/influxd/inspect/export_lp.go

@@ -98,8 +98,8 @@ func NewExportLineProtocolCommand(v *viper.Viper) (*cobra.Command, error) {
 This command will export all TSM data stored in a bucket
 to line protocol for inspection and re-ingestion.`,
 		Args: cobra.NoArgs,
-		RunE: func(*cobra.Command, []string) error {
-			return exportRunE(flags)
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			return exportRunE(cmd, flags)
 		},
 	}
 
@@ -134,7 +134,7 @@ to line protocol for inspection and re-ingestion.`,
 		{
 			DestP:    &flags.outputPath,
 			Flag:     "output-path",
-			Desc:     "path where exported line-protocol should be written",
+			Desc:     "path where exported line-protocol should be written. Use '-' to write to standard out",
 			Required: true,
 		},
 		{
@@ -155,7 +155,7 @@ to line protocol for inspection and re-ingestion.`,
 	return cmd, nil
 }
 
-func exportRunE(flags *exportFlags) error {
+func exportRunE(cmd *cobra.Command, flags *exportFlags) error {
 	logconf := zap.NewProductionConfig()
 	logconf.Level = zap.NewAtomicLevelAt(flags.logLevel)
 	logger, err := logconf.Build()
@@ -168,19 +168,25 @@ func exportRunE(flags *exportFlags) error {
 		return err
 	}
 
-	f, err := os.Create(flags.outputPath)
-	if err != nil {
-		return err
+	var w io.Writer
+	if flags.outputPath == "-" {
+		w = cmd.OutOrStdout()
+	} else {
+		f, err := os.Create(flags.outputPath)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		w = f
 	}
-	defer f.Close()
 
 	// Because calling (*os.File).Write is relatively expensive,
 	// and we don't *need* to sync to disk on every written line of export,
 	// use a sized buffered writer so that we only sync the file every megabyte.
-	bw := bufio.NewWriterSize(f, 1024*1024)
+	bw := bufio.NewWriterSize(w, 1024*1024)
 	defer bw.Flush()
+	w = bw
 
-	var w io.Writer = bw
 	if flags.compress {
 		gzw := gzip.NewWriter(w)
 		defer gzw.Close()