enable opentelemetry support

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

util/tracing/trace.go

@@ -0,0 +1,30 @@
+package tracing
+
+import (
+	"context"
+	"os"
+	"strings"
+
+	"github.com/moby/buildkit/util/tracing/detect"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+)
+
+func TraceCurrentCommand(ctx context.Context, name string) (context.Context, func(error), error) {
+	tp, err := detect.TracerProvider()
+	if err != nil {
+		return context.Background(), nil, err
+	}
+	ctx, span := tp.Tracer("").Start(ctx, name, trace.WithAttributes(
+		attribute.String("command", strings.Join(os.Args, " ")),
+	))
+
+	return ctx, func(err error) {
+		if err != nil {
+			span.RecordError(err)
+		}
+		span.End()
+
+		detect.Shutdown(context.TODO())
+	}, nil
+}