Add OpenTelemetry metric exporter integration

.gitignore

@@ -29,3 +29,4 @@ go.work
 # OS specific files
 .DS_Store
 Thumbs.db
+/docs/

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.0.0] - 2026-06-20
+
+### Added
+
+- `integrations/otelmetric`: opt-in OpenTelemetry metrics exporter. Implements `sdkmetric.Exporter` and bridges counters, gauges and histograms into the LogTide pipeline as log entries, inheriting the client's service name, environment, tags and resource attributes (closes #2)
+  - exemplar support: when a data point carries an exemplar with trace context, the entry is linked to that `trace_id`/`span_id` and the full exemplar list is recorded under `metadata.metric.exemplars`
+
 ## [0.9.4] - 2026-06-11
 
 ### Added

CONFORMANCE.md

@@ -33,3 +33,4 @@ why a scenario does not apply. TODO entries are tracked work.
 | C26 | log/trace correlation: active span ids on entries | ✅ | `tracing_test.go` (OTel context extraction) |
 | C27 | middleware error capture rethrows after logging | ✅ | `integrations/nethttp/nethttp_test.go` |
 | C28 | logging-bridge level mapping and scope context | ✅ | `integrations/logtideslog/logtideslog_test.go` |
+| C29 | OTLP metric export (counters/gauges/histograms) with resource attributes | ✅ | `integrations/otelmetric/otelmetric_test.go` (OTel-native path) |

README.md

@@ -24,7 +24,7 @@
 - **Automatic batching** — configurable batch size and flush interval
 - **Retry with backoff** — exponential backoff with jitter
 - **Circuit breaker** — prevents cascading failures
-- **OpenTelemetry** — trace/span IDs extracted automatically; span exporter included
+- **OpenTelemetry** — trace/span IDs extracted automatically; span and metric exporters included
 - **net/http middleware** — per-request scope isolation out of the box
 - **Thread-safe** — safe for concurrent use
 
@@ -224,6 +224,43 @@ tp := sdktrace.NewTracerProvider(
 )
 ```
 
+### Metric exporter
+
+Export OpenTelemetry metrics (counters, gauges, histograms) to LogTide. Each
+data point becomes a log entry carrying the same service name, environment, tags
+and resource attributes as your logs and traces. It is opt-in — register it only
+if you need metrics.
+
+```go
+import (
+    sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+
+    "github.com/logtide-dev/logtide-sdk-go/integrations/otelmetric"
+)
+
+integration := otelmetric.New()
+
+flush := logtide.Init(logtide.ClientOptions{
+    DSN:     "https://lp_abc@api.logtide.dev",
+    Service: "my-service",
+    Integrations: func(defaults []logtide.Integration) []logtide.Integration {
+        return append(defaults, integration)
+    },
+})
+defer flush()
+
+mp := sdkmetric.NewMeterProvider(
+    sdkmetric.WithReader(sdkmetric.NewPeriodicReader(integration.Exporter())),
+)
+otel.SetMeterProvider(mp)
+```
+
+When metric exemplars are enabled (an exemplar filter is configured and a sampled
+span is active during measurement), each linked data point's entry inherits the
+exemplar's `trace_id`/`span_id`, and the full exemplar list is recorded under
+`metadata.metric.exemplars` — correlating metrics with the traces that produced
+them.
+
 ---
 
 ## Flush & shutdown
@@ -278,6 +315,7 @@ client, _ := logtide.NewClient(logtide.ClientOptions{
 | [examples/echo](./examples/echo) | Echo framework integration |
 | [examples/stdlib](./examples/stdlib) | Standard library net/http |
 | [examples/otel](./examples/otel) | OpenTelemetry distributed tracing |
+| [examples/otelmetric](./examples/otelmetric) | OpenTelemetry metrics export |
 
 ---
 

examples/otelmetric/main.go

@@ -0,0 +1,88 @@
+// Command otelmetric demonstrates exporting OpenTelemetry metrics through
+// LogTide. Counters, gauges and histograms recorded against the MeterProvider
+// are converted to LogTide log entries carrying the same service name,
+// environment, tags and resource attributes as your logs and traces.
+package main
+
+import (
+	"context"
+	"log"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/metric"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+
+	logtide "github.com/logtide-dev/logtide-sdk-go"
+	"github.com/logtide-dev/logtide-sdk-go/integrations/otelmetric"
+)
+
+func main() {
+	// Create the metric integration and register it with LogTide.
+	integration := otelmetric.New()
+
+	flush := logtide.Init(logtide.ClientOptions{
+		DSN:     "https://lp_your_api_key_here@api.logtide.dev",
+		Service: "otelmetric-example",
+		Integrations: func(defaults []logtide.Integration) []logtide.Integration {
+			return append(defaults, integration)
+		},
+	})
+	defer flush()
+
+	// Wire the exporter into a MeterProvider. A PeriodicReader collects metrics
+	// on an interval and hands them to the exporter.
+	mp := sdkmetric.NewMeterProvider(
+		sdkmetric.WithReader(
+			sdkmetric.NewPeriodicReader(
+				integration.Exporter(),
+				sdkmetric.WithInterval(2*time.Second),
+			),
+		),
+	)
+	defer func() {
+		if err := mp.Shutdown(context.Background()); err != nil {
+			log.Printf("Error shutting down meter provider: %v", err)
+		}
+	}()
+	otel.SetMeterProvider(mp)
+
+	meter := mp.Meter("logtide-metric-example")
+
+	// A counter.
+	requests, err := meter.Int64Counter(
+		"http.requests",
+		metric.WithDescription("Number of handled HTTP requests"),
+		metric.WithUnit("1"),
+	)
+	if err != nil {
+		log.Fatalf("create counter: %v", err)
+	}
+
+	// A histogram.
+	latency, err := meter.Float64Histogram(
+		"http.latency",
+		metric.WithDescription("Request latency"),
+		metric.WithUnit("ms"),
+	)
+	if err != nil {
+		log.Fatalf("create histogram: %v", err)
+	}
+
+	ctx := context.Background()
+
+	// Record some measurements.
+	for i := 0; i < 5; i++ {
+		requests.Add(ctx, 1)
+		latency.Record(ctx, float64(40+i*7))
+		time.Sleep(200 * time.Millisecond)
+	}
+
+	// Force a final collection before exit so the metrics are flushed.
+	if err := mp.ForceFlush(ctx); err != nil {
+		log.Printf("force flush: %v", err)
+	}
+
+	log.Println("OpenTelemetry metrics example completed!")
+	log.Println("Counter and histogram values were exported to LogTide as log entries.")
+}

go.mod

@@ -3,7 +3,10 @@ module github.com/logtide-dev/logtide-sdk-go
 go 1.23.0
 
 require (
+	go.opentelemetry.io/otel v1.38.0
+	go.opentelemetry.io/otel/metric v1.38.0
 	go.opentelemetry.io/otel/sdk v1.38.0
+	go.opentelemetry.io/otel/sdk/metric v1.38.0
 	go.opentelemetry.io/otel/trace v1.38.0
 )
 
@@ -12,7 +15,5 @@ require (
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
-	go.opentelemetry.io/otel v1.38.0 // indirect
-	go.opentelemetry.io/otel/metric v1.38.0 // indirect
 	golang.org/x/sys v0.35.0 // indirect
 )