[FIX] Preserve user baggage header when setting Session ID

packages/core/src/rum/instrumentation/resourceTracking/__tests__/headers.test.ts

@@ -0,0 +1,14 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2016-Present Datadog, Inc.
+ */
+import { isDatadogCustomHeader } from '../headers';
+
+describe('headers', () => {
+    describe('isDatadogCustomHeader', () => {
+        it('returns false for non-custom headers', () => {
+            expect(isDatadogCustomHeader('non-custom-header')).toBeFalsy();
+        });
+    });
+});

packages/core/src/rum/instrumentation/resourceTracking/distributedTracing/distributedTracingHeaders.ts

@@ -48,9 +48,12 @@ export const getTracingHeadersFromAttributes = (
     if (tracingAttributes.tracingStrategy === 'DISCARD') {
         return headers;
     }
+
+    let hasDatadogOrW3CPropagator = false;
     tracingAttributes.propagatorTypes.forEach(propagator => {
         switch (propagator) {
             case PropagatorType.DATADOG: {
+                hasDatadogOrW3CPropagator = true;
                 headers.push(
                     {
                         header: ORIGIN_HEADER_KEY,
@@ -82,6 +85,7 @@ export const getTracingHeadersFromAttributes = (
                 break;
             }
             case PropagatorType.TRACECONTEXT: {
+                hasDatadogOrW3CPropagator = true;
                 const isSampled =
                     tracingAttributes.samplingPriorityHeader === '1';
                 headers.push(
@@ -137,14 +141,15 @@ export const getTracingHeadersFromAttributes = (
                 );
             }
         }
-        if (tracingAttributes.rumSessionId) {
-            headers.push({
-                header: BAGGAGE_HEADER_KEY,
-                value: `${DD_RUM_SESSION_ID_TAG}=${tracingAttributes.rumSessionId}`
-            });
-        }
     });
 
+    if (hasDatadogOrW3CPropagator && tracingAttributes.rumSessionId) {
+        headers.push({
+            header: BAGGAGE_HEADER_KEY,
+            value: `${DD_RUM_SESSION_ID_TAG}=${tracingAttributes.rumSessionId}`
+        });
+    }
+
     return headers;
 };
 

packages/core/src/rum/instrumentation/resourceTracking/graphql/__tests__/graphqlHeaders.test.ts

@@ -4,11 +4,11 @@
  * Copyright 2016-Present Datadog, Inc.
  */
 
+import { isDatadogCustomHeader } from '../../headers';
 import {
     DATADOG_GRAPH_QL_OPERATION_NAME_HEADER,
     DATADOG_GRAPH_QL_OPERATION_TYPE_HEADER,
-    DATADOG_GRAPH_QL_VARIABLES_HEADER,
-    isDatadogCustomHeader
+    DATADOG_GRAPH_QL_VARIABLES_HEADER
 } from '../graphqlHeaders';
 
 describe('GraphQL custom headers', () => {
@@ -19,10 +19,4 @@ describe('GraphQL custom headers', () => {
     ])('%s matches the custom header pattern', header => {
         expect(isDatadogCustomHeader(header)).toBeTruthy();
     });
-
-    describe('isDatadogCustomHeader', () => {
-        it('returns false for non-custom headers', () => {
-            expect(isDatadogCustomHeader('non-custom-header')).toBeFalsy();
-        });
-    });
 });

packages/core/src/rum/instrumentation/resourceTracking/graphql/graphqlHeaders.ts

@@ -1,15 +1,10 @@
+import { DATADOG_CUSTOM_HEADER_PREFIX } from '../headers';
+
 /*
  * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
  * This product includes software developed at Datadog (https://www.datadoghq.com/).
  * Copyright 2016-Present Datadog, Inc.
  */
-
-const DATADOG_CUSTOM_HEADER_PREFIX = '_dd-custom-header';
-
 export const DATADOG_GRAPH_QL_OPERATION_NAME_HEADER = `${DATADOG_CUSTOM_HEADER_PREFIX}-graph-ql-operation-name`;
 export const DATADOG_GRAPH_QL_VARIABLES_HEADER = `${DATADOG_CUSTOM_HEADER_PREFIX}-graph-ql-variables`;
 export const DATADOG_GRAPH_QL_OPERATION_TYPE_HEADER = `${DATADOG_CUSTOM_HEADER_PREFIX}-graph-ql-operation-type`;
-
-export const isDatadogCustomHeader = (header: string) => {
-    return header.match(new RegExp(`^${DATADOG_CUSTOM_HEADER_PREFIX}`));
-};

packages/core/src/rum/instrumentation/resourceTracking/headers.ts

@@ -0,0 +1,12 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2016-Present Datadog, Inc.
+ */
+
+export const DATADOG_CUSTOM_HEADER_PREFIX = '_dd-custom-header';
+export const DATADOG_BAGGAGE_HEADER = `${DATADOG_CUSTOM_HEADER_PREFIX}-baggage`;
+
+export const isDatadogCustomHeader = (header: string) => {
+    return header.match(new RegExp(`^${DATADOG_CUSTOM_HEADER_PREFIX}`));
+};

packages/core/src/rum/instrumentation/resourceTracking/requestProxy/XHRProxy/XHRProxy.ts

@@ -6,20 +6,24 @@
 
 import { Timer } from '../../../../../utils/Timer';
 import { getCachedSessionId } from '../../../../sessionId/sessionIdHelper';
-import { getTracingHeadersFromAttributes } from '../../distributedTracing/distributedTracingHeaders';
+import {
+    BAGGAGE_HEADER_KEY,
+    getTracingHeadersFromAttributes
+} from '../../distributedTracing/distributedTracingHeaders';
 import type { DdRumResourceTracingAttributes } from '../../distributedTracing/distributedTracing';
 import { getTracingAttributes } from '../../distributedTracing/distributedTracing';
 import {
     DATADOG_GRAPH_QL_OPERATION_NAME_HEADER,
     DATADOG_GRAPH_QL_OPERATION_TYPE_HEADER,
-    DATADOG_GRAPH_QL_VARIABLES_HEADER,
-    isDatadogCustomHeader
+    DATADOG_GRAPH_QL_VARIABLES_HEADER
 } from '../../graphql/graphqlHeaders';
+import { DATADOG_BAGGAGE_HEADER, isDatadogCustomHeader } from '../../headers';
 import type { RequestProxyOptions } from '../interfaces/RequestProxy';
 import { RequestProxy } from '../interfaces/RequestProxy';
 
 import type { ResourceReporter } from './DatadogRumResource/ResourceReporter';
 import { URLHostParser } from './URLHostParser';
+import { formatBaggageHeader } from './baggageHeaderUtils';
 import { calculateResponseSize } from './responseSize';
 
 const RESPONSE_START_LABEL = 'response_start';
@@ -39,6 +43,7 @@ interface DdRumXhrContext {
     reported: boolean;
     timer: Timer;
     tracingAttributes: DdRumResourceTracingAttributes;
+    baggageHeaderEntries: Set<string>;
 }
 
 interface XHRProxyProviders {
@@ -111,7 +116,8 @@ const proxyOpen = (
                 firstPartyHostsRegexMap,
                 tracingSamplingRate,
                 rumSessionId: getCachedSessionId()
-            })
+            }),
+            baggageHeaderEntries: new Set<string>()
         };
         // eslint-disable-next-line prefer-rest-params
         return originalXhrOpen.apply(this, arguments as any);
@@ -127,12 +133,22 @@ const proxySend = (providers: XHRProxyProviders): void => {
             // keep track of start time
             this._datadog_xhr.timer.start();
 
+            // Tracing Headers
             const tracingHeaders = getTracingHeadersFromAttributes(
                 this._datadog_xhr.tracingAttributes
             );
+
             tracingHeaders.forEach(({ header, value }) => {
                 this.setRequestHeader(header, value);
             });
+
+            // Join all baggage header entries
+            const baggageHeader = formatBaggageHeader(
+                this._datadog_xhr.baggageHeaderEntries
+            );
+            if (baggageHeader) {
+                this.setRequestHeader(DATADOG_BAGGAGE_HEADER, baggageHeader);
+            }
         }
 
         proxyOnReadyStateChange(this, providers);
@@ -211,22 +227,37 @@ const proxySetRequestHeader = (providers: XHRProxyProviders): void => {
         header: string,
         value: string
     ) {
-        if (isDatadogCustomHeader(header)) {
-            if (header === DATADOG_GRAPH_QL_OPERATION_NAME_HEADER) {
-                this._datadog_xhr.graphql.operationName = value;
-                return;
-            }
-            if (header === DATADOG_GRAPH_QL_OPERATION_TYPE_HEADER) {
-                this._datadog_xhr.graphql.operationType = value;
-                return;
-            }
-            if (header === DATADOG_GRAPH_QL_VARIABLES_HEADER) {
-                this._datadog_xhr.graphql.variables = value;
-                return;
+        const key = header.toLowerCase();
+        if (isDatadogCustomHeader(key)) {
+            switch (key) {
+                case DATADOG_GRAPH_QL_OPERATION_NAME_HEADER:
+                    this._datadog_xhr.graphql.operationName = value;
+                    break;
+                case DATADOG_GRAPH_QL_OPERATION_TYPE_HEADER:
+                    this._datadog_xhr.graphql.operationType = value;
+                    break;
+                case DATADOG_GRAPH_QL_VARIABLES_HEADER:
+                    this._datadog_xhr.graphql.variables = value;
+                    break;
+                case DATADOG_BAGGAGE_HEADER:
+                    // Apply Baggage Header only if pre-processed by Datadog
+                    return originalXhrSetRequestHeader.apply(this, [
+                        BAGGAGE_HEADER_KEY,
+                        value
+                    ]);
+                default:
+                    return originalXhrSetRequestHeader.apply(
+                        this,
+                        // eslint-disable-next-line prefer-rest-params
+                        arguments as any
+                    );
             }
+        } else if (key === BAGGAGE_HEADER_KEY) {
+            // Intercept User Baggage Header entries to apply them later
+            this._datadog_xhr.baggageHeaderEntries?.add(value);
+        } else {
+            // eslint-disable-next-line prefer-rest-params
+            return originalXhrSetRequestHeader.apply(this, arguments as any);
         }
-
-        // eslint-disable-next-line prefer-rest-params
-        return originalXhrSetRequestHeader.apply(this, arguments as any);
     };
 };

packages/core/src/rum/instrumentation/resourceTracking/requestProxy/XHRProxy/__tests__/XHRProxy.test.ts

@@ -839,6 +839,93 @@ describe('XHRProxy', () => {
             // THEN
             expect(xhr.requestHeaders[BAGGAGE_HEADER_KEY]).toBeUndefined();
         });
+
+        it('does not add rum session id to baggage headers when propagator type is not datadog or w3c', async () => {
+            // GIVEN
+            const method = 'GET';
+            const url = 'https://example.com';
+            xhrProxy.onTrackingStart({
+                tracingSamplingRate: 100,
+                firstPartyHostsRegexMap: firstPartyHostsRegexMapBuilder([
+                    {
+                        match: 'api.example.com',
+                        propagatorTypes: [
+                            PropagatorType.DATADOG,
+                            PropagatorType.TRACECONTEXT
+                        ]
+                    },
+                    {
+                        match: 'example.com', // <-- no datadog or tracecontext here
+                        propagatorTypes: [
+                            PropagatorType.B3,
+                            PropagatorType.B3MULTI
+                        ]
+                    }
+                ])
+            });
+
+            setCachedSessionId('TEST-SESSION-ID');
+
+            // WHEN
+            const xhr = new XMLHttpRequestMock();
+            xhr.open(method, url);
+            xhr.send();
+            xhr.notifyResponseArrived();
+            xhr.complete(200, 'ok');
+            await flushPromises();
+
+            // THEN
+            expect(xhr.requestHeaders[BAGGAGE_HEADER_KEY]).toBeUndefined();
+        });
+
+        it('rum session id does not overwrite existing baggage headers', async () => {
+            // GIVEN
+            const method = 'GET';
+            const url = 'https://api.example.com:443/v2/user';
+            xhrProxy.onTrackingStart({
+                tracingSamplingRate: 100,
+                firstPartyHostsRegexMap: firstPartyHostsRegexMapBuilder([
+                    {
+                        match: 'api.example.com',
+                        propagatorTypes: [
+                            PropagatorType.DATADOG,
+                            PropagatorType.TRACECONTEXT
+                        ]
+                    },
+                    {
+                        match: 'example.com',
+                        propagatorTypes: [
+                            PropagatorType.B3,
+                            PropagatorType.B3MULTI
+                        ]
+                    }
+                ])
+            });
+
+            setCachedSessionId('TEST-SESSION-ID');
+
+            // WHEN
+            const xhr = new XMLHttpRequestMock();
+            xhr.open(method, url);
+            xhr.setRequestHeader('baggage', 'existing.key=existing-value');
+            xhr.send();
+            xhr.notifyResponseArrived();
+            xhr.complete(200, 'ok');
+            await flushPromises();
+
+            // THEN
+            expect(xhr.requestHeaders[BAGGAGE_HEADER_KEY]).not.toBeUndefined();
+            expect(xhr.requestHeaders[BAGGAGE_HEADER_KEY]).toContain(
+                'existing.key=existing-value'
+            );
+
+            const values = xhr.requestHeaders[BAGGAGE_HEADER_KEY].split(
+                ','
+            ).sort();
+
+            expect(values[0]).toBe('existing.key=existing-value');
+            expect(values[1]).toBe('session.id=TEST-SESSION-ID');
+        });
     });
 
     describe('DdRum.startResource calls', () => {