Custom Instrumentation for Requests Module

Learn how to manually instrument your code to use Sentry's Requests module.

As a prerequisite to setting up Requests, you’ll need to first set up performance monitoring. Once this is done, the JavaScript SDK will automatically instrument outgoing HTTP requests. If that doesn't fit your use case, you can set up using custom instrumentation.

For detailed information about which data can be set, see the Requests Module developer specifications.

To use the SDK, initialize it in your Svelte entry point before bootstrapping your app. In a typical Svelte project, that is your main.js or main.ts file.

main.js
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import './app.css';
import App from './App.svelte';

import * as Sentry from '@sentry/svelte';

// Initialize the Sentry SDK here
Sentry.init({
  dsn: 'https://examplePublicKey@o0.ingest.sentry.io/0',
  integrations: [Sentry.browserTracingIntegration(), Sentry.replayIntegration()],

  // Set tracesSampleRate to 1.0 to capture 100%
  // of transactions for performance monitoring.
  // We recommend adjusting this value in production
  tracesSampleRate: 1.0,

  // Set `tracePropagationTargets` to control for which URLs distributed tracing should be enabled
  tracePropagationTargets: ['localhost', /^https:\/\/yourserver\.io\/api/],

  // Capture Replay for 10% of all sessions,
  // plus for 100% of sessions with an error
  replaysSessionSampleRate: 0.1,
  replaysOnErrorSampleRate: 1.0,
});

const app = new App({
  target: document.getElementById('app'),
});

export default app;

Once you've done this, the SDK will automatically capture unhandled errors and promise rejections, and monitor performance in the client. You can also manually capture errors.

NOTE: Refer to HTTP Span Data Conventions for a full list of the span data attributes.

Here is an example of an instrumented function that makes HTTP requests:

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async function makeRequest(method, url) {
  return await Sentry.startSpan(
    {op: 'http.client', name: `${method} ${url}`},
    async span => {
      const parsedURL = new URL(url, location.origin);

      const response = await fetch(url, {
        method,
      });

      span?.setAttribute('http.request.method', method);

      span?.setAttribute('server.address', parsedURL.hostname);
      span?.setAttribute('server.port', parsedURL.port || undefined);

      span?.setAttribute('http.response.status_code', response.status);
      span?.setAttribute(
        'http.response_content_length',
        Number(response.headers.get('content-length'))
      );

      // A good place to set other span attributes

      return response;
    }
  );
}
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