feat(browser): Add new v7 Fetch Transport (#4765)

This PR creates the new v7 Fetch Transport, and updates the browser backend to use the new transport. To configure the transport, users can supply `requestOptions`, which is supplied to the fetch request. This consolidates the earlier pattern of passing in both headers and fetchParameters that the old fetch transport used to use.

packages/browser/src/backend.ts

@@ -1,9 +1,9 @@
-import { BaseBackend } from '@sentry/core';
-import { Event, EventHint, Options, Severity, Transport } from '@sentry/types';
+import { BaseBackend, getEnvelopeEndpointWithUrlEncodedAuth, initAPIDetails } from '@sentry/core';
+import { Event, EventHint, Options, Severity, Transport, TransportOptions } from '@sentry/types';
 import { supportsFetch } from '@sentry/utils';
 
 import { eventFromException, eventFromMessage } from './eventbuilder';
-import { FetchTransport, XHRTransport } from './transports';
+import { FetchTransport, makeNewFetchTransport, XHRTransport } from './transports';
 
 /**
  * Configuration options for the Sentry Browser SDK.
@@ -58,18 +58,23 @@ export class BrowserBackend extends BaseBackend<BrowserOptions> {
       return super._setupTransport();
     }
 
-    const transportOptions = {
+    const transportOptions: TransportOptions = {
       ...this._options.transportOptions,
       dsn: this._options.dsn,
       tunnel: this._options.tunnel,
       sendClientReports: this._options.sendClientReports,
       _metadata: this._options._metadata,
     };
 
+    const api = initAPIDetails(transportOptions.dsn, transportOptions._metadata, transportOptions.tunnel);
+    const url = getEnvelopeEndpointWithUrlEncodedAuth(api.dsn, api.tunnel);
+
     if (this._options.transport) {
       return new this._options.transport(transportOptions);
     }
     if (supportsFetch()) {
+      const requestOptions: RequestInit = { ...transportOptions.fetchParameters };
+      this._newTransport = makeNewFetchTransport({ requestOptions, url });
       return new FetchTransport(transportOptions);
     }
     return new XHRTransport(transportOptions);

packages/browser/src/transports/index.ts

@@ -1,3 +1,5 @@
 export { BaseTransport } from './base';
 export { FetchTransport } from './fetch';
 export { XHRTransport } from './xhr';
+
+export { makeNewFetchTransport } from './new-fetch';

packages/browser/src/transports/new-fetch.ts

@@ -0,0 +1,44 @@
+import {
+  BaseTransportOptions,
+  createTransport,
+  NewTransport,
+  TransportMakeRequestResponse,
+  TransportRequest,
+} from '@sentry/core';
+
+import { FetchImpl, getNativeFetchImplementation } from './utils';
+
+export interface FetchTransportOptions extends BaseTransportOptions {
+  requestOptions?: RequestInit;
+}
+
+/**
+ * Creates a Transport that uses the Fetch API to send events to Sentry.
+ */
+export function makeNewFetchTransport(
+  options: FetchTransportOptions,
+  nativeFetch: FetchImpl = getNativeFetchImplementation(),
+): NewTransport {
+  function makeRequest(request: TransportRequest): PromiseLike<TransportMakeRequestResponse> {
+    const requestOptions: RequestInit = {
+      body: request.body,
+      method: 'POST',
+      referrerPolicy: 'origin',
+      ...options.requestOptions,
+    };
+
+    return nativeFetch(options.url, requestOptions).then(response => {
+      return response.text().then(body => ({
+        body,
+        headers: {
+          'x-sentry-rate-limits': response.headers.get('X-Sentry-Rate-Limits'),
+          'retry-after': response.headers.get('Retry-After'),
+        },
+        reason: response.statusText,
+        statusCode: response.status,
+      }));
+    });
+  }
+
+  return createTransport({ bufferSize: options.bufferSize }, makeRequest);
+}

packages/browser/test/unit/transports/new-fetch.test.ts

@@ -0,0 +1,98 @@
+import { EventEnvelope, EventItem } from '@sentry/types';
+import { createEnvelope, serializeEnvelope } from '@sentry/utils';
+
+import { FetchTransportOptions, makeNewFetchTransport } from '../../../src/transports/new-fetch';
+import { FetchImpl } from '../../../src/transports/utils';
+
+const DEFAULT_FETCH_TRANSPORT_OPTIONS: FetchTransportOptions = {
+  url: 'https://sentry.io/api/42/store/?sentry_key=123&sentry_version=7',
+};
+
+const ERROR_ENVELOPE = createEnvelope<EventEnvelope>({ event_id: 'aa3ff046696b4bc6b609ce6d28fde9e2', sent_at: '123' }, [
+  [{ type: 'event' }, { event_id: 'aa3ff046696b4bc6b609ce6d28fde9e2' }] as EventItem,
+]);
+
+class Headers {
+  headers: { [key: string]: string } = {};
+  get(key: string) {
+    return this.headers[key] || null;
+  }
+  set(key: string, value: string) {
+    this.headers[key] = value;
+  }
+}
+
+describe('NewFetchTransport', () => {
+  it('calls fetch with the given URL', async () => {
+    const mockFetch = jest.fn(() =>
+      Promise.resolve({
+        headers: new Headers(),
+        status: 200,
+        text: () => Promise.resolve({}),
+      }),
+    ) as unknown as FetchImpl;
+    const transport = makeNewFetchTransport(DEFAULT_FETCH_TRANSPORT_OPTIONS, mockFetch);
+
+    expect(mockFetch).toHaveBeenCalledTimes(0);
+    const res = await transport.send(ERROR_ENVELOPE);
+    expect(mockFetch).toHaveBeenCalledTimes(1);
+
+    expect(res.status).toBe('success');
+
+    expect(mockFetch).toHaveBeenLastCalledWith(DEFAULT_FETCH_TRANSPORT_OPTIONS.url, {
+      body: serializeEnvelope(ERROR_ENVELOPE),
+      method: 'POST',
+      referrerPolicy: 'origin',
+    });
+  });
+
+  it('sets rate limit headers', async () => {
+    const headers = {
+      get: jest.fn(),
+    };
+
+    const mockFetch = jest.fn(() =>
+      Promise.resolve({
+        headers,
+        status: 200,
+        text: () => Promise.resolve({}),
+      }),
+    ) as unknown as FetchImpl;
+    const transport = makeNewFetchTransport(DEFAULT_FETCH_TRANSPORT_OPTIONS, mockFetch);
+
+    expect(headers.get).toHaveBeenCalledTimes(0);
+    await transport.send(ERROR_ENVELOPE);
+
+    expect(headers.get).toHaveBeenCalledTimes(2);
+    expect(headers.get).toHaveBeenCalledWith('X-Sentry-Rate-Limits');
+    expect(headers.get).toHaveBeenCalledWith('Retry-After');
+  });
+
+  it('allows for custom options to be passed in', async () => {
+    const mockFetch = jest.fn(() =>
+      Promise.resolve({
+        headers: new Headers(),
+        status: 200,
+        text: () => Promise.resolve({}),
+      }),
+    ) as unknown as FetchImpl;
+
+    const REQUEST_OPTIONS: RequestInit = {
+      referrerPolicy: 'strict-origin',
+      keepalive: true,
+      referrer: 'http://example.org',
+    };
+
+    const transport = makeNewFetchTransport(
+      { ...DEFAULT_FETCH_TRANSPORT_OPTIONS, requestOptions: REQUEST_OPTIONS },
+      mockFetch,
+    );
+
+    await transport.send(ERROR_ENVELOPE);
+    expect(mockFetch).toHaveBeenLastCalledWith(DEFAULT_FETCH_TRANSPORT_OPTIONS.url, {
+      body: serializeEnvelope(ERROR_ENVELOPE),
+      method: 'POST',
+      ...REQUEST_OPTIONS,
+    });
+  });
+});

packages/integration-tests/suites/new-transports/fetch-captureException/subject.js

@@ -0,0 +1 @@
+Sentry.captureException(new Error('this is an error'));

packages/integration-tests/suites/new-transports/fetch-captureException/test.ts

@@ -0,0 +1,21 @@
+import { expect } from '@playwright/test';
+import { Event } from '@sentry/types';
+
+import { sentryTest } from '../../../utils/fixtures';
+import { getFirstSentryEnvelopeRequest } from '../../../utils/helpers';
+
+sentryTest('should capture an error with the new fetch transport', async ({ getLocalTestPath, page }) => {
+  const url = await getLocalTestPath({ testDir: __dirname });
+
+  const eventData = await getFirstSentryEnvelopeRequest<Event>(page, url);
+
+  expect(eventData.exception?.values).toHaveLength(1);
+  expect(eventData.exception?.values?.[0]).toMatchObject({
+    type: 'Error',
+    value: 'this is an error',
+    mechanism: {
+      type: 'generic',
+      handled: true,
+    },
+  });
+});

packages/integration-tests/suites/new-transports/fetch-startTransaction/subject.js

@@ -0,0 +1,2 @@
+const transaction = Sentry.startTransaction({ name: 'test_transaction_1' });
+transaction.finish();

packages/integration-tests/suites/new-transports/fetch-startTransaction/test.ts

@@ -0,0 +1,13 @@
+import { expect } from '@playwright/test';
+import { Event } from '@sentry/types';
+
+import { sentryTest } from '../../../utils/fixtures';
+import { getFirstSentryEnvelopeRequest } from '../../../utils/helpers';
+
+sentryTest('should report a transaction with the new fetch transport', async ({ getLocalTestPath, page }) => {
+  const url = await getLocalTestPath({ testDir: __dirname });
+  const transaction = await getFirstSentryEnvelopeRequest<Event>(page, url);
+
+  expect(transaction.transaction).toBe('test_transaction_1');
+  expect(transaction.spans).toBeDefined();
+});

packages/integration-tests/suites/new-transports/init.js

@@ -0,0 +1,13 @@
+import * as Sentry from '@sentry/browser';
+// eslint-disable-next-line no-unused-vars
+import * as _ from '@sentry/tracing';
+
+window.Sentry = Sentry;
+
+Sentry.init({
+  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+  _experiments: {
+    newTransport: true,
+  },
+  tracesSampleRate: 1.0,
+});