progress: explicitly fail if tty requested but not available

The NewPrinter function is mostly borrowed from buildkit. However, at
some point, it seems that the implementations drifted.

This patch updates buildx to be more similar in behavior to it's
buildkit counterpart, specifically, it will explicitly fail if a TTY
output is requested using "--progress=tty", but the output is not
available.

To gracefully fallback to plain progress in this scenario,
"--progress=plain" is required.

Signed-off-by: Justin Chadwell <me@jedevc.com>

util/progress/printer.go

@@ -11,6 +11,7 @@ import (
 	"github.com/moby/buildkit/client"
 	"github.com/moby/buildkit/util/progress/progressui"
 	"github.com/opencontainers/go-digest"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -69,7 +70,7 @@ func (p *Printer) ClearLogSource(v interface{}) {
 	}
 }
 
-func NewPrinter(ctx context.Context, w io.Writer, out console.File, mode string) *Printer {
+func NewPrinter(ctx context.Context, w io.Writer, out console.File, mode string) (*Printer, error) {
 	statusCh := make(chan *client.SolveStatus)
 	doneCh := make(chan struct{})
 
@@ -83,21 +84,26 @@ func NewPrinter(ctx context.Context, w io.Writer, out console.File, mode string)
 		mode = v
 	}
 
-	go func() {
-		var c console.Console
-		switch mode {
-		case PrinterModeQuiet:
-			w = io.Discard
-		case PrinterModeAuto, PrinterModeTty:
-			if cons, err := console.ConsoleFromFile(out); err == nil {
-				c = cons
+	var c console.Console
+	switch mode {
+	case PrinterModeQuiet:
+		w = io.Discard
+	case PrinterModeAuto, PrinterModeTty:
+		if cons, err := console.ConsoleFromFile(out); err == nil {
+			c = cons
+		} else {
+			if mode == PrinterModeTty {
+				return nil, errors.Wrap(err, "failed to get console")
 			}
 		}
+	}
+
+	go func() {
 		resumeLogs := logutil.Pause(logrus.StandardLogger())
 		// not using shared context to not disrupt display but let is finish reporting errors
 		pw.warnings, pw.err = progressui.DisplaySolveStatus(ctx, "", c, w, statusCh)
 		resumeLogs()
 		close(doneCh)
 	}()
-	return pw
+	return pw, nil
 }