sentry

Sentry

Sentry provides real-time application performance monitoring, distributed tracing, and code-level error diagnostics across frontend, backend, and mobile stacks.

When to Use

• Real-Time Application Error Monitoring: Capturing unhandled exceptions, stack traces, and runtime errors in production.
• End-to-End Performance Tracing: Measuring transaction durations, database queries, and distributed trace spans.
• Source Map Processing & De-Minification: Translating minified production bundle errors back to original TypeScript source lines.
• Session Replay & User Crash Feedback: Watching user sessions to reproduce difficult-to-catch client-side bugs.

Quick Start

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

Sentry.init({ dsn: "https://examplePublicKey@o0.ingest.sentry.io/0", tracesSampleRate: 1.0, });

try { myFunction(); } catch (e) { Sentry.captureException(e); }

## Core Concepts

### Node.js / Next.js SDK Initialization with Performance Tracing

Instrumenting application with trace sampling and error capture:

```typescript
import * as Sentry from "@sentry/node";

Sentry.init({
  dsn: process.env.SENTRY_DSN,
  environment: process.env.NODE_ENV || "production",
  release: "api-service@2026.1.0",
  tracesSampleRate: 0.1, // Sample 10% of transactions for performance metrics

  // Filter sensitive data before transmitting to Sentry
  beforeSend(event, hint) {
    if (event.request?.headers) {
      delete event.request.headers["authorization"];
      delete event.request.headers["cookie"];
    }
    return event;
  },
});

Manual Error Capture with Custom Context

Enriching errors with user context and custom tags:

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

async function processPayment(userId: string, amountCents: number) {
  try {
    // Simulated payment logic
    throw new Error("Payment gateway rejected authorization token");
  } catch (error) {
    Sentry.withScope((scope) => {
      scope.setUser({ id: userId });
      scope.setTag("payment.provider", "stripe");
      scope.setExtra("amount_cents", amountCents);
      scope.setLevel("error");

      Sentry.captureException(error);
    });
    throw error;
  }
}

Custom Performance Spans

Measuring execution duration of critical code blocks:

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

async function calculateRiskScore(orderId: string): Promise<number> {
  return await Sentry.startSpan(
    { name: "calculateRiskScore", op: "fraud.evaluation" },
    async (span) => {
      span.setAttribute("order_id", orderId);
      // Run intensive risk calculation
      return 0.95;
    },
  );
}

Common Patterns

Node.js / Express Error Middleware with User Context

Problem: Production exceptions logged without user session context or breadcrumb history.

Solution: Configure Sentry tracing and request isolation:

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

Sentry.init({
  dsn: process.env.SENTRY_DSN,
  tracesSampleRate: 0.2, // Capture 20% of transactions
  environment: process.env.NODE_ENV,
});

// Attach user context in auth middleware
app.use((req, res, next) => {
  if (req.user) {
    Sentry.setUser({ id: req.user.id, email: req.user.email });
  }
  next();
});

// Sentry error handler must be before any other error middleware
Sentry.setupExpressErrorHandler(app);

Best Practices

Do:

• Configure release tags to correlate error occurrences with specific Git commits and deployments.
• Upload source maps during CI/CD using @sentry/cli to get clear TypeScript line numbers in stack traces.
• Sanitize sensitive PII, credit card numbers, and authorization headers in beforeSend.
• Tune tracesSampleRate in high-throughput environments to prevent excessive ingestion costs.

Don't:

• Leave DSN keys exposed in public repositories without domain restriction rules.
• Catch exceptions silently without logging or passing to Sentry.captureException().
• Log high-frequency expected user validation errors (e.g. invalid form fields) as Sentry exceptions.

Troubleshooting

Error	Cause	Solution
Source maps not showing in stack traces	Source maps not uploaded during build or release version mismatch.	Upload source maps via @sentry/webpack-plugin with identical release tag.
Sentry DSN not capturing events	DSN variable missing in production runtime or rate limit exceeded.	Verify SENTRY_DSN is set and inspect Sentry Organization Stats for quota spikes.
Transactions flooded / quota exhausted	tracesSampleRate set to 1.0 (100%) on high-traffic production endpoints.	Reduce tracesSampleRate to 0.05 - 0.2 (5% - 20%).

References

• Sentry Documentation