Merge pull request moby#3058 from gsaraf/fix_ExportSpans_panic

Solve panic due to concurrent access to ExportSpans

Author: tonistiigi

util/tracing/detect/detect.go

@@ -73,21 +73,31 @@ func detectExporter() (sdktrace.SpanExporter, error) {
 	return nil, nil
 }
 
-func detect() error {
-	tp = trace.NewNoopTracerProvider()
-
+func getExporter() (sdktrace.SpanExporter, error) {
 	exp, err := detectExporter()
 	if err != nil {
-		return err
+		return nil, err
+	}
+
+	if exp != nil {
+		exp = &threadSafeExporterWrapper{
+			exporter: exp,
+		}
 	}
 
 	if Recorder != nil {
 		Recorder.SpanExporter = exp
 		exp = Recorder
 	}
+	return exp, nil
+}
+
+func detect() error {
+	tp = trace.NewNoopTracerProvider()
 
-	if exp == nil {
-		return nil
+	exp, err := getExporter()
+	if err != nil || exp == nil {
+		return err
 	}
 
 	// enable log with traceID when valid exporter

util/tracing/detect/threadsafe.go

@@ -0,0 +1,26 @@
+package detect
+
+import (
+	"context"
+	"sync"
+
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+)
+
+// threadSafeExporterWrapper wraps an OpenTelemetry SpanExporter and makes it thread-safe.
+type threadSafeExporterWrapper struct {
+	mu       sync.Mutex
+	exporter sdktrace.SpanExporter
+}
+
+func (tse *threadSafeExporterWrapper) ExportSpans(ctx context.Context, spans []sdktrace.ReadOnlySpan) error {
+	tse.mu.Lock()
+	defer tse.mu.Unlock()
+	return tse.exporter.ExportSpans(ctx, spans)
+}
+
+func (tse *threadSafeExporterWrapper) Shutdown(ctx context.Context) error {
+	tse.mu.Lock()
+	defer tse.mu.Unlock()
+	return tse.exporter.Shutdown(ctx)
+}