Support dumb terminals by turning off color (#6246)

ANSI colors do not work on dumb terminals, in situations
when minio is running as a service under systemd.

This PR ensures we turn off color in those situations.

cmd/globals.go

@@ -18,10 +18,12 @@ package cmd
 
 import (
 	"crypto/x509"
+	"fmt"
 	"os"
 	"runtime"
 	"time"
 
+	isatty "github.com/mattn/go-isatty"
 	"github.com/minio/minio-go/pkg/set"
 
 	etcd "github.com/coreos/etcd/clientv3"
@@ -219,12 +221,72 @@ var (
 
 // global colors.
 var (
-	colorBold     = color.New(color.Bold).SprintFunc()
+	// Check if we stderr, stdout are dumb terminals, we do not apply
-	colorRed      = color.New(color.FgRed).SprintfFunc()
+	// ansi coloring on dumb terminals.
-	colorBlue     = color.New(color.FgBlue).SprintfFunc()
+	isTerminal = func() bool {
-	colorYellow   = color.New(color.FgYellow).SprintfFunc()
+		return isatty.IsTerminal(os.Stdout.Fd()) && isatty.IsTerminal(os.Stderr.Fd())
-	colorBgYellow = color.New(color.BgYellow).SprintfFunc()
+	}
-	colorBlack    = color.New(color.FgBlack).SprintfFunc()
+
+	colorBold = func() func(a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.Bold).SprintFunc()
+		}
+		return fmt.Sprint
+	}()
+	colorRed = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgRed).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorBlue = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgBlue).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorYellow = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgYellow).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorCyanBold = func() func(a ...interface{}) string {
+		if isTerminal() {
+			color.New(color.FgCyan, color.Bold).SprintFunc()
+		}
+		return fmt.Sprint
+	}()
+	colorYellowBold = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgYellow, color.Bold).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorBgYellow = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.BgYellow).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorBlack = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgBlack).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorGreenBold = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgGreen, color.Bold).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorRedBold = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgRed, color.Bold).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
 )
 
 // Returns minio global information, as a key value map.

cmd/logger/utils.go

@@ -18,17 +18,45 @@ package logger
 
 import (
 	"fmt"
+	"os"
 	"regexp"
 
 	"github.com/fatih/color"
+	isatty "github.com/mattn/go-isatty"
 )
 
 // Global colors.
 var (
-	colorBold    = color.New(color.Bold).SprintFunc()
+	// Check if we stderr, stdout are dumb terminals, we do not apply
-	colorFgRed   = color.New(color.FgRed).SprintfFunc()
+	// ansi coloring on dumb terminals.
-	colorBgRed   = color.New(color.BgRed).SprintfFunc()
+	isTerminal = func() bool {
-	colorFgWhite = color.New(color.FgWhite).SprintfFunc()
+		return isatty.IsTerminal(os.Stdout.Fd()) && isatty.IsTerminal(os.Stderr.Fd())
+	}
+
+	colorBold = func() func(a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.Bold).SprintFunc()
+		}
+		return fmt.Sprint
+	}()
+	colorFgRed = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgRed).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorBgRed = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.BgRed).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
+	colorFgWhite = func() func(format string, a ...interface{}) string {
+		if isTerminal() {
+			return color.New(color.FgWhite).SprintfFunc()
+		}
+		return fmt.Sprintf
+	}()
 )
 
 var ansiRE = regexp.MustCompile("(\x1b[^m]*m)")
@@ -40,15 +68,21 @@ func ansiEscape(format string, args ...interface{}) {
 }
 
 func ansiMoveRight(n int) {
-	ansiEscape("[%dC", n)
+	if isTerminal() {
+		ansiEscape("[%dC", n)
+	}
 }
 
 func ansiSaveAttributes() {
-	ansiEscape("7")
+	if isTerminal() {
+		ansiEscape("7")
+	}
 }
 
 func ansiRestoreAttributes() {
-	ansiEscape("8")
+	if isTerminal() {
+		ansiEscape("8")
+	}
 }
 
 func uniqueEntries(paths []string) []string {

cmd/update-main.go

@@ -30,7 +30,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/fatih/color"
 	"github.com/inconshreveable/go-update"
 	"github.com/minio/cli"
 	"github.com/minio/minio/cmd/logger"
@@ -458,7 +457,7 @@ func getUpdateInfo(timeout time.Duration, mode string) (updateMsg string, sha256
 
 func doUpdate(sha256Hex string, latestReleaseTime time.Time, ok bool) (updateStatusMsg string, err error) {
 	if !ok {
-		updateStatusMsg = greenColorSprintf("Minio update to version RELEASE.%s canceled.",
+		updateStatusMsg = colorGreenBold("Minio update to version RELEASE.%s canceled.",
 			latestReleaseTime.Format(minioReleaseTagTimeLayout))
 		return updateStatusMsg, nil
 	}
@@ -484,21 +483,18 @@ func doUpdate(sha256Hex string, latestReleaseTime time.Time, ok bool) (updateSta
 		return updateStatusMsg, err
 	}
 
-	return greenColorSprintf("Minio updated to version RELEASE.%s successfully.",
+	return colorGreenBold("Minio updated to version RELEASE.%s successfully.",
 		latestReleaseTime.Format(minioReleaseTagTimeLayout)), nil
 }
 
 func shouldUpdate(quiet bool, sha256Hex string, latestReleaseTime time.Time) (ok bool) {
 	ok = true
 	if !quiet {
-		ok = prompt.Confirm(greenColorSprintf("Update to RELEASE.%s [%s]", latestReleaseTime.Format(minioReleaseTagTimeLayout), "yes"))
+		ok = prompt.Confirm(colorGreenBold("Update to RELEASE.%s [%s]", latestReleaseTime.Format(minioReleaseTagTimeLayout), "yes"))
 	}
 	return ok
 }
 
-var greenColorSprintf = color.New(color.FgGreen, color.Bold).SprintfFunc()
-var redColorSprintf = color.New(color.FgRed, color.Bold).SprintfFunc()
-
 func mainUpdate(ctx *cli.Context) {
 	if len(ctx.Args()) != 0 {
 		cli.ShowCommandHelpAndExit(ctx, "update", -1)
@@ -520,7 +516,7 @@ func mainUpdate(ctx *cli.Context) {
 
 	// Nothing to update running the latest release.
 	if updateMsg == "" {
-		logger.Info(greenColorSprintf("You are already running the most recent version of ‘minio’."))
+		logger.Info(colorGreenBold("You are already running the most recent version of ‘minio’."))
 		os.Exit(0)
 	}
 
@@ -531,7 +527,7 @@ func mainUpdate(ctx *cli.Context) {
 		var updateStatusMsg string
 		updateStatusMsg, err = doUpdate(sha256Hex, latestReleaseTime, shouldUpdate(quiet, sha256Hex, latestReleaseTime))
 		if err != nil {
-			logger.Info(redColorSprintf("Unable to update ‘minio’."))
+			logger.Info(colorRedBold("Unable to update ‘minio’."))
 			logger.Info(err.Error())
 			os.Exit(-1)
 		}

cmd/update-notifier.go

@@ -25,7 +25,6 @@ import (
 
 	"github.com/cheggaaa/pb"
 	humanize "github.com/dustin/go-humanize"
-	"github.com/fatih/color"
 )
 
 // prepareUpdateMessage - prepares the update message, only if a
@@ -46,10 +45,6 @@ func prepareUpdateMessage(downloadURL string, older time.Duration) string {
 
 // colorizeUpdateMessage - inspired from Yeoman project npm package https://github.com/yeoman/update-notifier
 func colorizeUpdateMessage(updateString string, newerThan string) string {
-	// Initialize coloring.
-	cyan := color.New(color.FgCyan, color.Bold).SprintFunc()
-	yellow := color.New(color.FgYellow, color.Bold).SprintfFunc()
-
 	msgLine1Fmt := " You are running an older version of Minio released %s "
 	msgLine2Fmt := " Update: %s "
 
@@ -59,8 +54,8 @@ func colorizeUpdateMessage(updateString string, newerThan string) string {
 	line2Length := len(fmt.Sprintf(msgLine2Fmt, updateString))
 
 	// Populate lines with color coding.
-	line1InColor := fmt.Sprintf(msgLine1Fmt, yellow(newerThan))
+	line1InColor := fmt.Sprintf(msgLine1Fmt, colorYellowBold(newerThan))
-	line2InColor := fmt.Sprintf(msgLine2Fmt, cyan(updateString))
+	line2InColor := fmt.Sprintf(msgLine2Fmt, colorCyanBold(updateString))
 
 	// calculate the rectangular box size.
 	maxContentWidth := int(math.Max(float64(line1Length), float64(line2Length)))
@@ -94,10 +89,10 @@ func colorizeUpdateMessage(updateString string, newerThan string) string {
 	}
 
 	lines := []string{
-		yellow(topLeftChar + strings.Repeat(horizBarChar, maxContentWidth) + topRightChar),
+		colorYellowBold(topLeftChar + strings.Repeat(horizBarChar, maxContentWidth) + topRightChar),
 		vertBarChar + line1InColor + strings.Repeat(" ", maxContentWidth-line1Length) + vertBarChar,
 		vertBarChar + line2InColor + strings.Repeat(" ", maxContentWidth-line2Length) + vertBarChar,
-		yellow(bottomLeftChar + strings.Repeat(horizBarChar, maxContentWidth) + bottomRightChar),
+		colorYellowBold(bottomLeftChar + strings.Repeat(horizBarChar, maxContentWidth) + bottomRightChar),
 	}
 	return "\n" + strings.Join(lines, "\n") + "\n"
 }