BookCars supports error monitoring through Sentry (https://sentry.io), which captures runtime exceptions and performance metrics. This is useful for diagnosing backend issues in production or staging environments.

1. Create a free account at https://sentry.io.
2. Create a new Node.js project in Sentry for the BookCars backend.
3. Copy the provided DSN URL.

Sentry integration is optional and controlled by environment variables in the backend.

BC_ENABLE_SENTRY=true
BC_SENTRY_DSN_BACKEND=https://your_dsn@o0.ingest.sentry.io/your_project_id
BC_SENTRY_TRACES_SAMPLE_RATE=0.1

Do not commit the real DSN to version control.

• When BC_ENABLE_SENTRY=true and BC_SENTRY_DSN_BACKEND is defined, the backend initializes Sentry at startup.
• Runtime errors (especially in try/catch blocks or unhandled routes) are automatically reported to Sentry.
• When BC_SENTRY_TRACES_SAMPLE_RATE is is greater than 0, transactions will be sent to Sentry. Sentry will capture performance transactions, showing request duration, slow routes, and trace spans. Set to 0 to disable tracing. 0.1 means 10% of transactions will be sent to Sentry. 1 means 100% of transactions will be sent to Sentry. We recommend adjusting this value in production.
• The integration complements the existing Winston-based logging system.

To verify Sentry is working:

1. Temporarily set BC_ENABLE_SENTRY=true and use a real DSN.
2. Trigger an error in a controller:

throw new Error('Test Sentry integration')

3. Check your Sentry dashboard under Issues.

• Sentry is only enabled if both:
  • BC_ENABLE_SENTRY=true
  • BC_SENTRY_DSN_BACKEND is set
• You can safely use BookCars without Sentry if you prefer other monitoring solutions.

• backend/src/monitoring/instrument.ts - Sentry integration and initialization
• backend/src/app.ts - Sentry Express middleware is attached if enabled
• backend/src/config/logger.ts - Automatically reports errors to Sentry if enabled