fix(otel): Prevent baggage from being overwritten

packages/opentelemetry-node/src/propagator.ts

@@ -1,17 +1,18 @@
 import {
+  Baggage,
   Context,
   isSpanContextValid,
+  propagation,
   TextMapGetter,
-  TextMapPropagator,
   TextMapSetter,
   trace,
   TraceFlags,
 } from '@opentelemetry/api';
-import { isTracingSuppressed } from '@opentelemetry/core';
+import { isTracingSuppressed, W3CBaggagePropagator } from '@opentelemetry/core';
 import {
   baggageHeaderToDynamicSamplingContext,
-  dynamicSamplingContextToSentryBaggageHeader,
   extractTraceparentData,
+  SENTRY_BAGGAGE_KEY_PREFIX,
 } from '@sentry/utils';
 
 import {
@@ -25,7 +26,7 @@ import { SENTRY_SPAN_PROCESSOR_MAP } from './spanprocessor';
 /**
  * Injects and extracts `sentry-trace` and `baggage` headers from carriers.
  */
-export class SentryPropagator implements TextMapPropagator {
+export class SentryPropagator extends W3CBaggagePropagator {
   /**
    * @inheritDoc
    */
@@ -41,10 +42,18 @@ export class SentryPropagator implements TextMapPropagator {
 
       if (span.transaction) {
         const dynamicSamplingContext = span.transaction.getDynamicSamplingContext();
-        const sentryBaggageHeader = dynamicSamplingContextToSentryBaggageHeader(dynamicSamplingContext);
-        if (sentryBaggageHeader) {
-          setter.set(carrier, SENTRY_BAGGAGE_HEADER, sentryBaggageHeader);
-        }
+
+        const baggage = propagation.getBaggage(context) || propagation.createBaggage({});
+        const baggageWithSentryInfo = Object.entries(dynamicSamplingContext).reduce<Baggage>(
+          (b, [dscKey, dscValue]) => {
+            if (dscValue) {
+              return b.setEntry(`${SENTRY_BAGGAGE_KEY_PREFIX}${dscKey}`, { value: dscValue });
+            }
+            return b;
+          },
+          baggage,
+        );
+        super.inject(propagation.setBaggage(context, baggageWithSentryInfo), carrier, setter);
       }
     }
   }

packages/opentelemetry-node/test/propagator.test.ts

@@ -1,4 +1,11 @@
-import { defaultTextMapGetter, defaultTextMapSetter, ROOT_CONTEXT, trace, TraceFlags } from '@opentelemetry/api';
+import {
+  defaultTextMapGetter,
+  defaultTextMapSetter,
+  propagation,
+  ROOT_CONTEXT,
+  trace,
+  TraceFlags,
+} from '@opentelemetry/api';
 import { suppressTracing } from '@opentelemetry/core';
 import { Hub, makeMain } from '@sentry/core';
 import { addExtensionMethods, Transaction } from '@sentry/tracing';
@@ -138,6 +145,27 @@ describe('SentryPropagator', () => {
           expect(carrier[SENTRY_TRACE_HEADER]).toBe(sentryTrace);
         });
 
+        it('should include existing baggage', () => {
+          const transactionContext = {
+            name: 'sampled-transaction',
+            traceId: 'd4cda95b652f4a1592b449d5929fda1b',
+            spanId: '6e0c63257de34c92',
+            sampled: true,
+          };
+          const spanContext = {
+            traceId: 'd4cda95b652f4a1592b449d5929fda1b',
+            spanId: '6e0c63257de34c92',
+            traceFlags: TraceFlags.SAMPLED,
+          };
+          createTransactionAndMaybeSpan(type, transactionContext);
+          const context = trace.setSpanContext(ROOT_CONTEXT, spanContext);
+          const baggage = propagation.createBaggage({ foo: { value: 'bar' } });
+          propagator.inject(propagation.setBaggage(context, baggage), carrier, defaultTextMapSetter);
+          expect(carrier[SENTRY_BAGGAGE_HEADER]).toBe(
+            'foo=bar,sentry-environment=production,sentry-release=1.0.0,sentry-transaction=sampled-transaction,sentry-public_key=abc,sentry-trace_id=d4cda95b652f4a1592b449d5929fda1b',
+          );
+        });
+
         it('should NOT set baggage and sentry-trace header if instrumentation is supressed', () => {
           const spanContext = {
             traceId: 'd4cda95b652f4a1592b449d5929fda1b',