Sentry sdk patterns

Sentry SDK Patterns

Overview

Production patterns for @sentry/node (v8+) and sentry-sdk (Python 2.x+) covering scoped error context, breadcrumb strategies, event filtering with beforeSend, custom fingerprinting for issue grouping, and performance instrumentation with spans. All examples use real Sentry SDK APIs.

Prerequisites

• Sentry SDK v8+ installed (@sentry/node, @sentry/react, or sentry-sdk)
• SENTRY_DSN environment variable configured
• Familiarity with async/await (TypeScript) or context managers (Python)

Instructions

Step 1 -- Structured Error Context with Scopes

Use Sentry.withScope() (TypeScript) or sentry_sdk.new_scope() (Python) to attach context to individual events without leaking state across requests.

TypeScript -- Scoped error capture:

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

type ErrorSeverity = 'low' | 'medium' | 'high' | 'critical';

interface ErrorOptions {
  severity?: ErrorSeverity;
  tags?: Record<string, string>;
  context?: Record<string, unknown>;
  user?: { id: string; email?: string };
  fingerprint?: string[];
}

const SEVERITY_MAP: Record<ErrorSeverity, Sentry.SeverityLevel> = {
  low: 'info',
  medium: 'warning',
  high: 'error',
  critical: 'fatal',
};

export function captureError(error: Error, options: ErrorOptions = {}) {
  Sentry.withScope((scope) => {
    scope.setLevel(SEVERITY_MAP[options.severity || 'medium']);

    if (options.tags) {
      Object.entries(options.tags).forEach(([key, value]) => {
        scope.setTag(key, value);
      });
    }
    if (options.context) {
      scope.setContext('app', options.context);
    }
    if (options.user) {
      scope.setUser(options.user);
    }
    if (options.fingerprint) {
      scope.setFingerprint(options.fingerprint);
    }

    Sentry.captureException(error);
  });
}

Python -- Scoped error capture:

import sentry_sdk

def capture_error(error, severity="error", tags=None, context=None, user=None):
    """Capture exception with isolated scope context."""
    with sentry_sdk.new_scope() as scope:
        scope.set_level(severity)
        if tags:
            for key, value in tags.items():
                scope.set_tag(key, value)
        if context:
            scope.set_context("app", context)
        if user:
            scope.set_user(user)
        sentry_sdk.capture_exception(error)

Key rule: Never call Sentry.setTag() or sentry_sdk.set_tag() at the module level inside request handlers. Those mutate the global scope and leak between concurrent requests. Always use withScope() or new_scope().

Step 2 -- Breadcrumbs, Filtering, and Fingerprints

Structured breadcrumb helpers

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

export const breadcrumb = {
  auth(action: string, userId?: string) {
    Sentry.addBreadcrumb({
      category: 'auth',
      message: `${action}${userId ? ` for user ${userId}` : ''}`,
      level: 'info',
    });
  },

  db(operation: string, table: string, durationMs?: number) {
    Sentry.addBreadcrumb({
      category: 'db',
      message: `${operation} on ${table}`,
      level: 'info',
      data: { table, operation, ...(durationMs && { duration_ms: durationMs }) },
    });
  },

  http(method: string, url: string, status: number) {
    Sentry.addBreadcrumb({
      category: 'http',
      message: `${method} ${url} -> ${status}`,
      level: status >= 400 ? 'warning' : 'info',
      data: { method, url, status_code: status },
    });
  },
};

Python breadcrumbs:

sentry_sdk.add_breadcrumb(
    category="auth", message="User logged in",
    level="info", data={"user_id": user_id, "method": "oauth"},
)

beforeSend -- Drop noise, scrub PII

Sentry.init({
  dsn: process.env.SENTRY_DSN,
  beforeSend(event, hint) {
    const error = hint?.originalException;
    // Drop non-actionable errors
    if (error instanceof Error) {
      if (error.message.includes('ResizeObserver loop')) return null;
      if (error.message.includes('Network request failed')) return null;
    }
    // Scrub PII from user context
    if (event.user) {
      delete event.user.ip_address;
      delete event.user.email;
    }
    return event;
  },
});

Python beforeSend:

def before_send(event, hint):
    if "exc_info" in hint:
        exc_type, exc_value, tb = hint["exc_info"]
        if isinstance(exc_value, (KeyboardInterrupt, SystemExit)):
            return None
    if "user" in event:
        event["user"].pop("email", None)
        event["user"].pop("ip_address", None)
    return event

sentry_sdk.init(dsn=os.environ["SENTRY_DSN"], before_send=before_send)

beforeBreadcrumb -- Filter noisy breadcrumbs

Sentry.init({
  dsn: process.env.SENTRY_DSN,
  beforeBreadcrumb(breadcrumb, hint) {
    // Drop console.log breadcrumbs in production
    if (breadcrumb.category === 'console' && breadcrumb.level === 'log') {
      return null;
    }
    // Redact auth tokens from HTTP breadcrumbs
    if (breadcrumb.category === 'fetch' && breadcrumb.data?.url) {
      const url = new URL(breadcrumb.data.url);
      url.searchParams.delete('token');
      breadcrumb.data.url = url.toString();
    }
    return breadcrumb;
  },
});

Custom fingerprints for issue grouping

Override default stack-trace grouping when the same root cause produces different stacks:

Sentry.withScope((scope) => {
  // Group all payment gateway timeouts together
  scope.setFingerprint(['payment-gateway-timeout', gatewayName]);
  Sentry.captureException(error);
});

with sentry_sdk.new_scope() as scope:
    scope.fingerprint = ["payment-gateway-timeout", gateway_name]
    sentry_sdk.capture_exception(error)

Step 3 -- Framework Integration and Performance Spans

Express middleware (Sentry v8)

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

const app = express();

// Sentry v8: register error handler
Sentry.setupExpressErrorHandler(app);

// Request context middleware (register BEFORE routes)
app.use((req, res, next) => {
  Sentry.setUser({ id: req.user?.id, ip_address: req.ip });
  Sentry.addBreadcrumb({
    category: 'http',
    message: `${req.method} ${req.path}`,
    data: { query: req.query, params: req.params },
  });
  next();
});

React Error Boundary

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

const SentryErrorBoundary = Sentry.withErrorBoundary(App, {
  fallback: ({ error, resetError }) => (
    <div>
      <h2>Something went wrong</h2>
      <button onClick={resetError}>Try again</button>
    </div>
  ),
  beforeCapture: (scope) => {
    scope.setTag('location', 'error-boundary');
    scope.setLevel('fatal');
  },
});

Performance spans (TypeScript)

async function processOrder(orderId: string) {
  return Sentry.startSpan(
    { name: 'processOrder', op: 'task', attributes: { orderId } },
    async (span) => {
      const order = await Sentry.startSpan(
        { name: 'db.getOrder', op: 'db.query' },
        () => db.orders.findById(orderId),
      );
      await Sentry.startSpan(
        { name: 'payment.charge', op: 'http.client' },
        () => chargePayment(order),
      );
      span.setStatus({ code: 1, message: 'ok' });
      return order;
    },
  );
}

Performance spans (Python)

import sentry_sdk
from functools import wraps

def sentry_traced(op="function"):
    """Decorator to wrap functions in Sentry spans."""
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            with sentry_sdk.start_span(op=op, name=func.__name__):
                return func(*args, **kwargs)
        return wrapper
    return decorator

@sentry_traced(op="db.query")
def get_user(user_id: str):
    return db.users.find_one({"_id": user_id})

Async batch processing with error isolation

async function processItems(items: Item[]) {
  const results = await Promise.allSettled(
    items.map((item) =>
      Sentry.startSpan({ name: `process.${item.type}`, op: 'task' }, () =>
        processItem(item),
      ),
    ),
  );

  const failures = results.filter(
    (r): r is PromiseRejectedResult => r.status === 'rejected',
  );

  if (failures.length > 0) {
    Sentry.withScope((scope) => {
      scope.setTag('batch_size', String(items.length));
      scope.setTag('failure_count', String(failures.length));
      Sentry.captureMessage(`${failures.length}/${items.length} items failed`, 'warning');
    });
    failures.forEach((f) => Sentry.captureException(f.reason));
  }
}

See implementation.md for Django middleware, test mocking patterns, and additional framework examples.

Output

After applying these patterns you will have:

• Centralized error handler module with typed severity and scoped context
• Structured breadcrumb helpers for auth, db, and http events
• beforeSend filter that drops noise and scrubs PII
• beforeBreadcrumb callback that redacts sensitive query parameters
• Custom fingerprinting for accurate issue grouping
• Framework error boundaries for Express and React
• Performance spans for tracing critical code paths

Error Handling

Error	Cause	Solution
Scope leaking between requests	Global scope mutations in async handlers	Use withScope() / new_scope() for per-event context
Duplicate events	Error caught and re-thrown at two layers	Capture at one level only -- middleware or handler, not both
Missing breadcrumbs	Cleared after max count (default 100)	Set maxBreadcrumbs in Sentry.init()
beforeSend returns undefined	Missing return statement	Always return event or null explicitly
Events grouped incorrectly	Default stack-trace fingerprinting	Use scope.setFingerprint() with semantic keys
Sentry is not defined	SDK not imported	Verify import * as Sentry from '@sentry/node'
Spans not appearing	Missing tracing config	Set tracesSampleRate in Sentry.init()

Examples

Centralized error handler: Create lib/error-handler.ts wrapping Sentry.withScope() with typed severity, tags, context, user, and fingerprint support.

Breadcrumb trail for checkout: Add breadcrumb.auth('login'), breadcrumb.db('SELECT', 'orders'), breadcrumb.http('POST', '/api/payments', 201) before critical operations so errors include full context timeline.

Noise filtering: Configure beforeSend to drop ResizeObserver loop and Network request failed, scrub PII from user context and cookies.

Fix issue grouping: Add scope.setFingerprint(['payment-gateway-timeout', gatewayName]) to group all payment timeouts by gateway.

See examples.md for full worked scenarios with Python context managers and async wrappers.

Resources

• Sentry JavaScript SDK Best Practices
• Scopes and Context
• Express Integration Guide
• Python SDK Documentation
• Custom Fingerprinting
• Performance Monitoring

Next Steps

• sentry-error-capture -- Deep dive on captureException vs captureMessage semantics
• sentry-performance-tracing -- Full distributed tracing with tracesSampleRate and custom instrumentation
• sentry-data-handling -- PII scrubbing, data residency, and GDPR-compliant configuration
• sentry-common-errors -- Troubleshooting guide for frequent SDK issues