Monitoring

Set up monitoring for your saga-based applications.

Key Metrics

Monitor these essential metrics for saga health:

Metric	Description	Alert Threshold
saga_messages_processed_total	Total messages processed	N/A (use rate)
saga_message_processing_duration_seconds	Handler execution time	p99 > 5s
saga_messages_failed_total	Failed message count	> 0/min
saga_active_instances	Currently running sagas	Depends on load
saga_dlq_messages_total	Dead letter queue size	> 0

Prometheus Setup

import { createMetricsMiddleware } from '@saga-bus/middleware-metrics';

const bus = createBus({
  transport,
  store,
  sagas,
  middleware: [
    createMetricsMiddleware({
      prefix: 'saga_bus',
      labels: ['saga_name', 'message_type'],
    }),
  ],
});

Grafana Dashboard

Key panels to include:

1. Message Throughput - Messages processed per second
2. Processing Latency - p50, p95, p99 duration histograms
3. Error Rate - Failed messages over time
4. Active Sagas - Current saga instance count
5. DLQ Depth - Dead letter queue size

Alerting Rules

groups:
  - name: saga-bus
    rules:
      - alert: HighErrorRate
        expr: rate(saga_messages_failed_total[5m]) > 0.01
        for: 5m
        labels:
          severity: warning

      - alert: SlowProcessing
        expr: histogram_quantile(0.99, saga_message_processing_duration_seconds) > 5
        for: 10m
        labels:
          severity: warning

      - alert: DLQNotEmpty
        expr: saga_dlq_messages_total > 0
        for: 1m
        labels:
          severity: critical

See Also

• Metrics Middleware
• Tracing Middleware
• Observability