---
title: Observability
description: Prometheus metrics and OpenTelemetry tracing.
---

The `observability` package provides Prometheus metrics and OpenTelemetry tracing for monitoring Relay in production.

## Prometheus metrics

```go
import "github.com/xraph/relay/observability"

metrics := observability.NewMetrics(prometheus.DefaultRegisterer)
```

### Available metrics

| Metric | Type | Description |
|--------|------|-------------|
| `relay_events_sent_total` | Counter | Total events submitted |
| `relay_deliveries_total` | CounterVec | Delivery attempts by status (`delivered`, `failed`, `retried`) |
| `relay_delivery_latency_seconds` | Histogram | HTTP request latency per delivery |
| `relay_dlq_size` | Gauge | Current DLQ entries |
| `relay_pending_deliveries` | Gauge | Current pending deliveries |

### Recording deliveries

```go
metrics.RecordDelivery("delivered", 0.245)
metrics.RecordDelivery("failed", 1.023)
```

## OpenTelemetry tracing

```go
import "github.com/xraph/relay/observability"

tracer := observability.NewTracer()

ctx, span := tracer.StartDeliverySpan(ctx, deliveryID, eventID, endpointID)
defer tracer.EndDeliverySpan(span, statusCode, latencyMs, errMsg)
```

Each delivery span includes attributes:
- `relay.delivery_id`
- `relay.event_id`
- `relay.endpoint_id`
- `http.status_code`
- `relay.latency_ms`
- `relay.error` (if present)