feat(core): Add sampling decision to trace envelope header

Author: AbhiPrasad

packages/core/src/tracing/transaction.ts

@@ -264,6 +264,10 @@ export class Transaction extends SpanClass implements TransactionInterface {
       dsc.transaction = this.name;
     }
 
+    if (this.sampled !== undefined) {
+      dsc.sampled = String(this.sampled);
+    }
+
     // Uncomment if we want to make DSC immutable
     // this._frozenDynamicSamplingContext = dsc;
 

packages/node/test/integrations/http.test.ts

@@ -116,7 +116,8 @@ describe('tracing', () => {
     expect(baggageHeader).toEqual(
       'sentry-environment=production,sentry-release=1.0.0,' +
         'sentry-user_segment=segmentA,sentry-public_key=dogsarebadatkeepingsecrets,' +
-        'sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1,sentry-transaction=dogpark',
+        'sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1,' +
+        'sentry-transaction=dogpark,sentry-sampled=true',
     );
   });
 
@@ -128,10 +129,10 @@ describe('tracing', () => {
     const request = http.get({ host: 'http://dogs.are.great/', headers: { baggage: 'dog=great' } });
     const baggageHeader = request.getHeader('baggage') as string;
 
-    expect(baggageHeader).toEqual([
-      'dog=great',
-      'sentry-environment=production,sentry-release=1.0.0,sentry-user_segment=segmentA,sentry-public_key=dogsarebadatkeepingsecrets,sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1,sentry-transaction=dogpark',
-    ]);
+    expect(baggageHeader[0]).toEqual('dog=great');
+    expect(baggageHeader[1]).toEqual(
+      'sentry-environment=production,sentry-release=1.0.0,sentry-user_segment=segmentA,sentry-public_key=dogsarebadatkeepingsecrets,sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1,sentry-transaction=dogpark,sentry-sampled=true',
+    );
   });
 
   it('adds the transaction name to the the baggage header if a valid transaction source is set', async () => {
@@ -144,7 +145,7 @@ describe('tracing', () => {
 
     expect(baggageHeader).toEqual([
       'dog=great',
-      'sentry-environment=production,sentry-release=1.0.0,sentry-user_segment=segmentA,sentry-public_key=dogsarebadatkeepingsecrets,sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1,sentry-transaction=dogpark',
+      'sentry-environment=production,sentry-release=1.0.0,sentry-user_segment=segmentA,sentry-public_key=dogsarebadatkeepingsecrets,sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1,sentry-transaction=dogpark,sentry-sampled=true',
     ]);
   });
 
@@ -158,7 +159,7 @@ describe('tracing', () => {
 
     expect(baggageHeader).toEqual([
       'dog=great',
-      'sentry-environment=production,sentry-release=1.0.0,sentry-user_segment=segmentA,sentry-public_key=dogsarebadatkeepingsecrets,sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1',
+      'sentry-environment=production,sentry-release=1.0.0,sentry-user_segment=segmentA,sentry-public_key=dogsarebadatkeepingsecrets,sentry-trace_id=12312012123120121231201212312012,sentry-sample_rate=1,sentry-sampled=true',
     ]);
   });
 

packages/node/test/integrations/undici.test.ts

@@ -204,7 +204,7 @@ conditionalTest({ min: 16 })('Undici integration', () => {
 
     expect(requestHeaders['sentry-trace']).toEqual(span?.toTraceparent());
     expect(requestHeaders['baggage']).toEqual(
-      `sentry-environment=production,sentry-public_key=0,sentry-trace_id=${transaction.traceId},sentry-sample_rate=1,sentry-transaction=test-transaction`,
+      `sentry-environment=production,sentry-public_key=0,sentry-trace_id=${transaction.traceId},sentry-sample_rate=1,sentry-transaction=test-transaction,sentry-sampled=true`,
     );
   });
 

packages/tracing-internal/test/browser/browsertracing.test.ts

@@ -636,6 +636,7 @@ conditionalTest({ min: 10 })('BrowserTracing', () => {
           release: '1.0.0',
           environment: 'production',
           public_key: 'pubKey',
+          sampled: 'false',
           trace_id: expect.not.stringMatching('12312012123120121231201212312012'),
         });
       });

packages/types/src/envelope.ts

@@ -20,6 +20,7 @@ export type DynamicSamplingContext = {
   transaction?: string;
   user_segment?: string;
   replay_id?: string;
+  sampled?: string;
 };
 
 export type EnvelopeItemType =