feat: Add tunnel support to multiplexed transport

packages/core/src/baseclient.ts

@@ -141,6 +141,7 @@ export abstract class BaseClient<O extends ClientOptions> implements Client<O> {
         options._metadata ? options._metadata.sdk : undefined,
       );
       this._transport = options.transport({
+        tunnel: this._options.tunnel,
         recordDroppedEvent: this.recordDroppedEvent.bind(this),
         ...options.transportOptions,
         url,

packages/core/src/transports/multiplexed.ts

@@ -7,7 +7,7 @@ import type {
   Transport,
   TransportMakeRequestResponse,
 } from '@sentry/types';
-import { dsnFromString, forEachEnvelopeItem } from '@sentry/utils';
+import { createEnvelope, dsnFromString, forEachEnvelopeItem } from '@sentry/utils';
 
 import { getEnvelopeEndpointWithUrlEncodedAuth } from '../api';
 
@@ -57,6 +57,7 @@ function makeOverrideReleaseTransport<TO extends BaseTransportOptions>(
     const transport = createTransport(options);
 
     return {
+      ...transport,
       send: async (envelope: Envelope): Promise<TransportMakeRequestResponse> => {
         const event = eventFromEnvelope(envelope, ['event', 'transaction', 'profile', 'replay_event']);
 
@@ -65,11 +66,23 @@ function makeOverrideReleaseTransport<TO extends BaseTransportOptions>(
         }
         return transport.send(envelope);
       },
-      flush: timeout => transport.flush(timeout),
     };
   };
 }
 
+/** Overrides the DSN in the envelope header  */
+function overrideDsn(envelope: Envelope, dsn: string): Envelope {
+  return createEnvelope(
+    dsn
+      ? {
+          ...envelope[0],
+          dsn,
+        }
+      : envelope[0],
+    envelope[1],
+  );
+}
+
 /**
  * Creates a transport that can send events to different DSNs depending on the envelope contents.
  */
@@ -79,26 +92,30 @@ export function makeMultiplexedTransport<TO extends BaseTransportOptions>(
 ): (options: TO) => Transport {
   return options => {
     const fallbackTransport = createTransport(options);
-    const otherTransports: Record<string, Transport> = {};
+    const otherTransports: Map<string, Transport> = new Map();
 
-    function getTransport(dsn: string, release: string | undefined): Transport | undefined {
+    function getTransport(dsn: string, release: string | undefined): [string, Transport] | undefined {
       // We create a transport for every unique dsn/release combination as there may be code from multiple releases in
       // use at the same time
       const key = release ? `${dsn}:${release}` : dsn;
 
-      if (!otherTransports[key]) {
+      let transport = otherTransports.get(key);
+
+      if (!transport) {
         const validatedDsn = dsnFromString(dsn);
         if (!validatedDsn) {
           return undefined;
         }
-        const url = getEnvelopeEndpointWithUrlEncodedAuth(validatedDsn);
+        const url = getEnvelopeEndpointWithUrlEncodedAuth(validatedDsn, options.tunnel);
 
-        otherTransports[key] = release
+        transport = release
           ? makeOverrideReleaseTransport(createTransport, release)({ ...options, url })
           : createTransport({ ...options, url });
+
+        otherTransports.set(key, transport);
       }
 
-      return otherTransports[key];
+      return [dsn, transport];
     }
 
     async function send(envelope: Envelope): Promise<TransportMakeRequestResponse> {
@@ -115,20 +132,23 @@ export function makeMultiplexedTransport<TO extends BaseTransportOptions>(
             return getTransport(result.dsn, result.release);
           }
         })
-        .filter((t): t is Transport => !!t);
+        .filter((t): t is [string, Transport] => !!t);
 
       // If we have no transports to send to, use the fallback transport
       if (transports.length === 0) {
-        transports.push(fallbackTransport);
+        // Don't override the DSN in the header for the fallback transport. '' is falsy
+        transports.push(['', fallbackTransport]);
       }
 
-      const results = await Promise.all(transports.map(transport => transport.send(envelope)));
+      const results = await Promise.all(
+        transports.map(([dsn, transport]) => transport.send(overrideDsn(envelope, dsn))),
+      );
 
       return results[0];
     }
 
     async function flush(timeout: number | undefined): Promise<boolean> {
-      const allTransports = [...Object.keys(otherTransports).map(dsn => otherTransports[dsn]), fallbackTransport];
+      const allTransports = [...otherTransports.values(), fallbackTransport];
       const results = await Promise.all(allTransports.map(transport => transport.flush(timeout)));
       return results.every(r => r);
     }

packages/core/test/lib/transports/multiplexed.test.ts

@@ -1,6 +1,7 @@
 import type {
   BaseTransportOptions,
   ClientReport,
+  Envelope,
   EventEnvelope,
   EventItem,
   TransactionEvent,
@@ -47,7 +48,7 @@ const CLIENT_REPORT_ENVELOPE = createClientReportEnvelope(
   123456,
 );
 
-type Assertion = (url: string, release: string | undefined, body: string | Uint8Array) => void;
+type Assertion = (url: string, release: string | undefined, body: Envelope) => void;
 
 const createTestTransport = (...assertions: Assertion[]): ((options: BaseTransportOptions) => Transport) => {
   return (options: BaseTransportOptions) =>
@@ -60,7 +61,7 @@ const createTestTransport = (...assertions: Assertion[]): ((options: BaseTranspo
 
         const event = eventFromEnvelope(parseEnvelope(request.body), ['event']);
 
-        assertion(options.url, event?.release, request.body);
+        assertion(options.url, event?.release, parseEnvelope(request.body));
         resolve({ statusCode: 200 });
       });
     });
@@ -105,11 +106,12 @@ describe('makeMultiplexedTransport', () => {
   });
 
   it('DSN can be overridden via match callback', async () => {
-    expect.assertions(1);
+    expect.assertions(2);
 
     const makeTransport = makeMultiplexedTransport(
-      createTestTransport(url => {
+      createTestTransport((url, _, env) => {
         expect(url).toBe(DSN2_URL);
+        expect(env[0].dsn).toBe(DSN2);
       }),
       () => [DSN2],
     );
@@ -119,12 +121,13 @@ describe('makeMultiplexedTransport', () => {
   });
 
   it('DSN and release can be overridden via match callback', async () => {
-    expect.assertions(2);
+    expect.assertions(3);
 
     const makeTransport = makeMultiplexedTransport(
-      createTestTransport((url, release) => {
+      createTestTransport((url, release, env) => {
         expect(url).toBe(DSN2_URL);
         expect(release).toBe('something@1.0.0');
+        expect(env[0].dsn).toBe(DSN2);
       }),
       () => [{ dsn: DSN2, release: 'something@1.0.0' }],
     );
@@ -133,6 +136,22 @@ describe('makeMultiplexedTransport', () => {
     await transport.send(ERROR_ENVELOPE);
   });
 
+  it('URL can be overridden by tunnel option', async () => {
+    expect.assertions(3);
+
+    const makeTransport = makeMultiplexedTransport(
+      createTestTransport((url, release, env) => {
+        expect(url).toBe('http://google.com');
+        expect(release).toBe('something@1.0.0');
+        expect(env[0].dsn).toBe(DSN2);
+      }),
+      () => [{ dsn: DSN2, release: 'something@1.0.0' }],
+    );
+
+    const transport = makeTransport({ url: DSN1_URL, ...transportOptions, tunnel: 'http://google.com' });
+    await transport.send(ERROR_ENVELOPE);
+  });
+
   it('match callback can return multiple DSNs', async () => {
     expect.assertions(2);
 

packages/types/src/transport.ts

@@ -15,6 +15,12 @@ export type TransportMakeRequestResponse = {
 };
 
 export interface InternalBaseTransportOptions {
+  /**
+   * @ignore
+   * Users should pass the tunnel property via the init/client options.
+   * This is only used by the SDK to pass the tunnel to the transport.
+   */
+  tunnel?: string;
   bufferSize?: number;
   recordDroppedEvent: Client['recordDroppedEvent'];
 }