Scalable n8n CRM-Sync mit Error-Handling & Observability

// n8n Webhook-Node: JSON-Schema Validation
{
  "requestId": "uuid-v4",
  "eventType": "contact.created",
  "timestamp": "2026-02-08T10:00:00Z",
  "data": {
    "email": "[email protected]",
    "firstname": "Max",
    "lastname": "Mustermann"
  }
}

// Function-Node: Retry mit Exponential Backoff
const retryCount = $input.item.json.retryCount || 0;
const maxRetries = 5;
const baseDelay = 2000; // 2 seconds

if (retryCount {'<'} maxRetries) {
  const delay = baseDelay * Math.pow(2, retryCount);
  await new Promise(resolve ={'>'} setTimeout(resolve, delay));
  return { retryCount: retryCount + 1 };
} else {
  // Nach 5 Versuchen: Dead Letter Queue
  throw new Error('Max retries exceeded');
}

-- PostgreSQL Schema
CREATE TABLE sync_transactions (
  request_id VARCHAR(36) PRIMARY KEY,
  event_type VARCHAR(50),
  status VARCHAR(20), -- 'pending', 'success', 'failed'
  created_at TIMESTAMP DEFAULT NOW(),
  updated_at TIMESTAMP DEFAULT NOW()
);

-- n8n: Prüfung vor Sync
SELECT * FROM sync_transactions WHERE request_id = $json.requestId;
-- Wenn gefunden: SKIP, sonst INSERT und PROCEED

// Redis Token-Bucket Pattern
const tokenKey = 'hubspot:tokens';
const maxTokens = 100;
const refillRate = 10; // tokens per second

// Vor jedem API-Call: Token holen
const tokens = await redis.get(tokenKey) || maxTokens;
if (tokens {'>'} 0) {
  await redis.decr(tokenKey);
  // API-Call durchführen
} else {
  // Warten bis Tokens verfügbar
  await sleep(1000);
}