Error Tracking

Sentry (Node.js / Express)

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

Sentry.init({
  dsn: process.env.SENTRY_DSN,
  environment: process.env.NODE_ENV,
  release: process.env.APP_VERSION,
  tracesSampleRate: process.env.NODE_ENV === 'production' ? 0.1 : 1.0,
  integrations: [Sentry.expressIntegration()],
});

// Must be first middleware
app.use(Sentry.expressErrorHandler());

// Add context
app.use((req, res, next) => {
  Sentry.setUser({ id: req.user?.id, email: req.user?.email });
  Sentry.setTag('tenant', req.tenantId);
  next();
});

// Manual capture
try {
  await riskyOperation();
} catch (error) {
  Sentry.captureException(error, {
    extra: { orderId, userId },
    tags: { component: 'payment' },
  });
}

Sentry (React)

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

Sentry.init({
  dsn: process.env.NEXT_PUBLIC_SENTRY_DSN,
  environment: process.env.NODE_ENV,
  integrations: [Sentry.browserTracingIntegration(), Sentry.replayIntegration()],
  tracesSampleRate: 0.1,
  replaysSessionSampleRate: 0.1,
  replaysOnErrorSampleRate: 1.0,
});

// Error boundary
const SentryErrorBoundary = Sentry.withErrorBoundary(App, {
  fallback: <ErrorPage />,
  showDialog: true,
});

// Component-level
const ProfilePage = Sentry.withProfiler(Profile);

Sentry (Python)

import sentry_sdk
from sentry_sdk.integrations.fastapi import FastApiIntegration

sentry_sdk.init(
    dsn=os.environ["SENTRY_DSN"],
    environment=os.environ.get("ENV", "development"),
    traces_sample_rate=0.1,
    integrations=[FastApiIntegration()],
)

Sentry (Spring Boot)

<dependency>
  <groupId>io.sentry</groupId>
  <artifactId>sentry-spring-boot-starter-jakarta</artifactId>
</dependency>

sentry:
  dsn: ${SENTRY_DSN}
  environment: ${SPRING_PROFILES_ACTIVE}
  traces-sample-rate: 0.1

Source Maps Upload (CI/CD)

# GitHub Actions
- name: Upload source maps to Sentry
  run: |
    npx @sentry/cli sourcemaps upload \
      --release=${{ github.sha }} \
      --org=my-org --project=my-app \
      ./dist
  env:
    SENTRY_AUTH_TOKEN: ${{ secrets.SENTRY_AUTH_TOKEN }}

Breadcrumbs

Sentry.addBreadcrumb({
  category: 'payment',
  message: `Processing payment for order ${orderId}`,
  level: 'info',
  data: { orderId, amount },
});

Anti-Patterns

Anti-Pattern	Fix
100% trace sample rate in production	Use 0.1-0.2 for production
No source maps uploaded	Upload in CI/CD for readable stack traces
No release tracking	Set release to git SHA or version
Capturing expected errors	Only capture unexpected errors
No user context	Set user ID/email for debugging
PII in error data	Scrub sensitive fields in beforeSend

Production Checklist

• DSN configured per environment
• Source maps uploaded in CI/CD
• Release version set to git SHA
• Sample rate tuned (0.1-0.2 for production)
• User context attached
• Alert rules configured for error spikes
• PII scrubbing enabled