From a4f282c8e83a2447f22cdf230d90f0e91df880b6 Mon Sep 17 00:00:00 2001
From: Ben Johnson <benbjohnson@yahoo.com>
Date: Wed, 19 May 2021 15:04:36 -0600
Subject: [PATCH] Allow backup to stdout

---
 cmd/backup.go |  4 ++--
 ctl/backup.go | 24 ++++++++++++++++--------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/cmd/backup.go b/cmd/backup.go
index 8e272c526..d91975aa5 100644
--- a/cmd/backup.go
+++ b/cmd/backup.go
@@ -28,7 +28,7 @@ func newBackupCommand(stdin io.Reader, stdout io.Writer, stderr io.Writer) *cobr
 		Use:   "backup",
 		Short: "Back up pilosa server",
 		Long: `
-Backs up a pilosa server to a local snapshot file.
+Backs up a pilosa server to a local, tar-formatted snapshot file.
 `,
 		RunE: func(c *cobra.Command, args []string) error {
 			return cmd.Run(context.Background())
@@ -36,7 +36,7 @@ Backs up a pilosa server to a local snapshot file.
 	}
 
 	flags := ccmd.Flags()
-	flags.StringVarP(&cmd.OutputPath, "output", "o", "", "output path to write to")
+	flags.StringVarP(&cmd.OutputPath, "output", "o", "", "output path to write to; specify '-' to send to stdout")
 	flags.StringVar(&cmd.Host, "host", "localhost:10101", "host:port of Pilosa.")
 	ctl.SetTLSConfig(flags, "", &cmd.TLS.CertificatePath, &cmd.TLS.CertificateKeyPath, &cmd.TLS.CACertPath, &cmd.TLS.SkipVerify, &cmd.TLS.EnableClientVerification)
 	return ccmd
diff --git a/ctl/backup.go b/ctl/backup.go
index de8599020..644b295f6 100644
--- a/ctl/backup.go
+++ b/ctl/backup.go
@@ -73,6 +73,7 @@ func (cmd *BackupCommand) Run(ctx context.Context) (err error) {
 	if cmd.OutputPath == "" {
 		return fmt.Errorf("-o flag required")
 	}
+	useStdout := cmd.OutputPath == "-"
 
 	// Parse TLS configuration for node-specific clients.
 	tls := cmd.TLSConfiguration()
@@ -94,12 +95,17 @@ func (cmd *BackupCommand) Run(ctx context.Context) (err error) {
 	}
 	schema := &pilosa.Schema{Indexes: indexes}
 
-	// Create output file in temporary location.
-	w, err := os.Create(cmd.OutputPath + ".tmp")
-	if err != nil {
-		return err
+	// Create output file in temporary location, or send to stdout if a dash is specified.
+	var w io.Writer
+	if useStdout {
+		w = os.Stdout
+	} else {
+		f, err := os.Create(cmd.OutputPath + ".tmp")
+		if err != nil {
+			return err
+		}
+		defer f.Close()
 	}
-	defer w.Close()
 
 	// Open a tar writer to the temporary file.
 	tw := tar.NewWriter(w)
@@ -125,9 +131,11 @@ func (cmd *BackupCommand) Run(ctx context.Context) (err error) {
 	}
 
 	// Move data file to final location.
-	logger.Printf("writing backup: %s", cmd.OutputPath)
-	if err := os.Rename(cmd.OutputPath+".tmp", cmd.OutputPath); err != nil {
-		return err
+	if !useStdout {
+		logger.Printf("writing backup: %s", cmd.OutputPath)
+		if err := os.Rename(cmd.OutputPath+".tmp", cmd.OutputPath); err != nil {
+			return err
+		}
 	}
 
 	return nil