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