internal/telemetry: don't create internal spans without parents (#33780)

This prevents orphaned spans from appearing in traces.

internal/telemetry/telemetry.go

@@ -52,6 +52,11 @@ func StartSpan(ctx context.Context, spanName string, attributes ...Attribute) (c
 
 // StartSpanWithTracer requires a tracer to be passed in and creates a SpanKind=INTERNAL span.
 func StartSpanWithTracer(ctx context.Context, tracer trace.Tracer, name string, attributes ...Attribute) (context.Context, trace.Span, func(*error)) {
+	// Don't create a span if there's no parent span in the context.
+	parent := trace.SpanFromContext(ctx)
+	if !parent.SpanContext().IsValid() {
+		return ctx, parent, func(*error) {}
+	}
 	return startSpan(ctx, tracer, trace.SpanKindInternal, name, attributes...)
 }
 

internal/telemetry/telemetry_test.go

@@ -0,0 +1,98 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package telemetry
+
+import (
+	"context"
+	"testing"
+
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// newTestTracer creates a TracerProvider backed by an in-memory exporter.
+func newTestTracer(t *testing.T) (trace.Tracer, *sdktrace.TracerProvider, *tracetest.InMemoryExporter) {
+	t.Helper()
+	exporter := tracetest.NewInMemoryExporter()
+	tp := sdktrace.NewTracerProvider(sdktrace.WithSyncer(exporter))
+	t.Cleanup(func() { _ = tp.Shutdown(context.Background()) })
+	return tp.Tracer("test"), tp, exporter
+}
+
+func TestStartSpanWithTracer_NoParent(t *testing.T) {
+	t.Parallel()
+	tracer, tp, exporter := newTestTracer(t)
+
+	// Create a span without a parent.
+	ctx := context.Background()
+	retCtx, _, endSpan := StartSpanWithTracer(ctx, tracer, "should-not-exist")
+	endSpan(nil)
+
+	// The returned context should be the original context (unchanged).
+	if retCtx != ctx {
+		t.Fatal("expected original context to be returned unchanged")
+	}
+
+	// Flush and verify no spans were recorded.
+	if err := tp.ForceFlush(context.Background()); err != nil {
+		t.Fatalf("failed to flush: %v", err)
+	}
+	spans := exporter.GetSpans()
+	if len(spans) != 0 {
+		t.Fatalf("expected no spans, got %d", len(spans))
+	}
+}
+
+func TestStartSpanWithTracer_WithParent(t *testing.T) {
+	t.Parallel()
+	tracer, tp, exporter := newTestTracer(t)
+
+	// Create a parent span to establish a valid span context.
+	ctx, parentSpan := tracer.Start(context.Background(), "parent")
+	defer parentSpan.End()
+
+	// Should create a real child span.
+	_, _, endSpan := StartSpanWithTracer(ctx, tracer, "child")
+	endSpan(nil)
+
+	// Flush and verify the child span was recorded.
+	parentSpan.End()
+	if err := tp.ForceFlush(context.Background()); err != nil {
+		t.Fatalf("failed to flush: %v", err)
+	}
+	spans := exporter.GetSpans()
+	var childSpan *tracetest.SpanStub
+	for i := range spans {
+		if spans[i].Name == "child" {
+			childSpan = &spans[i]
+			break
+		}
+	}
+	if childSpan == nil {
+		t.Fatal("child span not found")
+	}
+
+	// Verify it is parented to the correct trace.
+	if childSpan.Parent.TraceID() != parentSpan.SpanContext().TraceID() {
+		t.Errorf("trace ID mismatch: got %s, want %s",
+			childSpan.Parent.TraceID(), parentSpan.SpanContext().TraceID())
+	}
+	if childSpan.SpanKind != trace.SpanKindInternal {
+		t.Errorf("expected SpanKindInternal, got %v", childSpan.SpanKind)
+	}
+}