fix(opentelemetry): Ignore invalid parent spans (#14512)

We do not align with how OTEL traces and the default samplers handle
invalid span contexts today.
If a span context is invalid, e.g. the span ID or trace ID are invalid,
then the span is ignored for new spans as a parent, and the new span
will start a new trace. This change aligns our own sampling strategy
with this, to ensure that invalid parent span contexts are ignored.

packages/opentelemetry/src/sampler.ts

@@ -48,7 +48,7 @@ export class SentrySampler implements Sampler {
   ): SamplingResult {
     const options = this._client.getOptions();
 
-    const parentSpan = trace.getSpan(context);
+    const parentSpan = getValidSpan(context);
     const parentContext = parentSpan?.spanContext();
 
     if (!hasTracingEnabled(options)) {
@@ -210,3 +210,12 @@ function getBaseTraceState(context: Context, spanAttributes: SpanAttributes): Tr
 
   return traceState;
 }
+
+/**
+ * If the active span is invalid, we want to ignore it as parent.
+ * This aligns with how otel tracers and default samplers handle these cases.
+ */
+function getValidSpan(context: Context): Span | undefined {
+  const span = trace.getSpan(context);
+  return span && isSpanContextValid(span.spanContext()) ? span : undefined;
+}

packages/opentelemetry/test/trace.test.ts

@@ -1450,6 +1450,27 @@ describe('trace (sampling)', () => {
       },
     });
   });
+
+  it('ignores parent span context if it is invalid', () => {
+    mockSdkInit({ tracesSampleRate: 1 });
+    const traceId = 'd4cda95b652f4a1592b449d5929fda1b';
+
+    const spanContext = {
+      traceId,
+      spanId: 'INVALID',
+      traceFlags: TraceFlags.SAMPLED,
+    };
+
+    context.with(trace.setSpanContext(ROOT_CONTEXT, spanContext), () => {
+      startSpan({ name: 'outer' }, span => {
+        expect(span.isRecording()).toBe(true);
+        expect(span.spanContext().spanId).not.toBe('INVALID');
+        expect(span.spanContext().spanId).toMatch(/[a-f0-9]{16}/);
+        expect(span.spanContext().traceId).not.toBe(traceId);
+        expect(span.spanContext().traceId).toMatch(/[a-f0-9]{32}/);
+      });
+    });
+  });
 });
 
 describe('HTTP methods (sampling)', () => {