Allow IsTerminal passthrough for SyncLogger

log/sync.go

@@ -42,6 +42,11 @@ type SyncWriter struct {
 	w  io.Writer
 }
 
+// ChildWriter returns the associated child io.Writer.
+func (w *SyncWriter) ChildWriter() io.Writer {
+	return w.w
+}
+
 // NewSyncWriter returns a new SyncWriter. The returned writer is safe for
 // concurrent use by multiple goroutines.
 func NewSyncWriter(w io.Writer) *SyncWriter {

log/sync_test.go

@@ -70,3 +70,13 @@ func TestSyncWriterConcurrency(t *testing.T) {
 	w = log.NewSyncWriter(w)
 	testConcurrency(t, log.NewLogfmtLogger(w), 10000)
 }
+
+func TestSyncWriterChildWriter(t *testing.T) {
+	want := &bytes.Buffer{}
+	w := log.NewSyncWriter(want)
+	got := w.ChildWriter()
+
+	if got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+}

log/term/colorwriter_windows.go

@@ -25,12 +25,14 @@ type colorWriter struct {
 // platform support for ANSI color codes. If w is not a terminal it is
 // returned unmodified.
 func NewColorWriter(w io.Writer) io.Writer {
-	if !IsTerminal(w) {
+	cw := resolveWriter(w)
+
+	if !IsTerminal(cw) {
 		return w
 	}
 
 	var csbi consoleScreenBufferInfo
-	handle := syscall.Handle(w.(fder).Fd())
+	handle := syscall.Handle(cw.(fder).Fd())
 	procGetConsoleScreenBufferInfo.Call(uintptr(handle), uintptr(unsafe.Pointer(&csbi)))
 
 	return &colorWriter{

log/term/term.go

@@ -7,11 +7,23 @@ import (
 	"github.com/go-kit/kit/log"
 )
 
+type parentWriter interface {
+	ChildWriter() io.Writer
+}
+
+func resolveWriter(w io.Writer) io.Writer {
+	if w, ok := w.(parentWriter); ok {
+		return resolveWriter(w.ChildWriter())
+	}
+
+	return w
+}
+
 // NewLogger returns a Logger that takes advantage of terminal features if
 // possible. Log events are formatted by the Logger returned by newLogger. If
 // w is a terminal each log event is colored according to the color function.
 func NewLogger(w io.Writer, newLogger func(io.Writer) log.Logger, color func(keyvals ...interface{}) FgBgColor) log.Logger {
-	if !IsTerminal(w) {
+	if !IsTerminal(resolveWriter(w)) {
 		return newLogger(w)
 	}
 	return NewColorLogger(NewColorWriter(w), newLogger, color)