4.6 KiB
4.6 KiB
Metrics
OpenTelemetry-compatible metrics for monitoring and alerting.
Overview
Svrnty.CQRS provides comprehensive metrics using System.Diagnostics.Metrics:
- Event Counters - Published, consumed, errors
- Processing Metrics - Latency, throughput
- Consumer Metrics - Lag, active consumers
- Projection Metrics - Progress, errors
Quick Start
using Svrnty.CQRS.Events;
using OpenTelemetry.Metrics;
var builder = WebApplication.CreateBuilder(args);
// Register event stream metrics
builder.Services.AddEventStreamMetrics();
// Configure OpenTelemetry
builder.Services.AddOpenTelemetry()
.WithMetrics(metrics => metrics
.AddMeter("Svrnty.CQRS.Events")
.AddPrometheusExporter());
var app = builder.Build();
// Export metrics at /metrics
app.MapPrometheusScrapingEndpoint();
app.Run();
Available Metrics
Event Metrics
// Counter: Total events published
svrnty_cqrs_events_published_total{stream="orders", event_type="OrderPlaced"}
// Counter: Total events consumed
svrnty_cqrs_events_consumed_total{stream="orders", subscription="email-processor"}
// Counter: Total errors
svrnty_cqrs_events_errors_total{stream="orders", error_type="ValidationError"}
// Counter: Total retries
svrnty_cqrs_events_retries_total{stream="orders"}
Performance Metrics
// Histogram: Processing latency in milliseconds
svrnty_cqrs_events_processing_latency{stream="orders", subscription="email-processor"}
// Histogram: Publish latency
svrnty_cqrs_events_publish_latency{stream="orders"}
// Gauge: Events per second
svrnty_cqrs_events_per_second{stream="orders"}
Consumer Metrics
// Gauge: Consumer lag (events behind)
svrnty_cqrs_consumer_lag{stream="orders", consumer="worker-1"}
// Gauge: Active consumers
svrnty_cqrs_active_consumers{stream="orders", group="order-processors"}
// Gauge: Stream length
svrnty_cqrs_stream_length{stream="orders"}
Recording Metrics
public class EventStreamMetrics
{
private readonly Meter _meter;
private readonly Counter<long> _eventsPublished;
private readonly Counter<long> _eventsConsumed;
private readonly Histogram<double> _processingLatency;
private readonly ObservableGauge<long> _consumerLag;
public EventStreamMetrics()
{
_meter = new Meter("Svrnty.CQRS.Events", "1.0.0");
_eventsPublished = _meter.CreateCounter<long>(
"svrnty.cqrs.events.published",
description: "Total events published");
_eventsConsumed = _meter.CreateCounter<long>(
"svrnty.cqrs.events.consumed",
description: "Total events consumed");
_processingLatency = _meter.CreateHistogram<double>(
"svrnty.cqrs.events.processing_latency",
unit: "ms",
description: "Event processing latency");
_consumerLag = _meter.CreateObservableGauge<long>(
"svrnty.cqrs.consumer.lag",
() => GetConsumerLagMeasurements(),
description: "Consumer lag in events");
}
public void RecordEventPublished(string streamName, string eventType)
{
_eventsPublished.Add(1,
new KeyValuePair<string, object?>("stream", streamName),
new KeyValuePair<string, object?>("event_type", eventType));
}
public void RecordEventConsumed(string streamName, string subscriptionId)
{
_eventsConsumed.Add(1,
new KeyValuePair<string, object?>("stream", streamName),
new KeyValuePair<string, object?>("subscription", subscriptionId));
}
public void RecordProcessingLatency(string streamName, TimeSpan duration)
{
_processingLatency.Record(duration.TotalMilliseconds,
new KeyValuePair<string, object?>("stream", streamName));
}
}
Prometheus Integration
// Add Prometheus exporter
builder.Services.AddOpenTelemetry()
.WithMetrics(metrics => metrics
.AddMeter("Svrnty.CQRS.Events")
.AddPrometheusExporter());
app.MapPrometheusScrapingEndpoint("/metrics");
// Query metrics:
// curl http://localhost:5000/metrics
Grafana Dashboards
# Events per second by stream
rate(svrnty_cqrs_events_published_total[1m])
# Consumer lag
svrnty_cqrs_consumer_lag
# P95 processing latency
histogram_quantile(0.95, rate(svrnty_cqrs_events_processing_latency_bucket[5m]))
# Error rate
rate(svrnty_cqrs_events_errors_total[5m])