feat: add Tracer and Meter for components

Author: sysulq

example_test.go

@@ -15,7 +15,7 @@ import (
 )
 
 // This example demonstrates how to use [kod.Run] and [kod.Implements] to run a simple application.
-func Example_mainComponent() {
+func Example_componentMain() {
 	kod.Run(context.Background(), func(ctx context.Context, app *helloworld.App) error {
 		fmt.Println("Hello, World!")
 		return nil
@@ -92,8 +92,8 @@ func Example_configGlobal() {
 	// helloWorld shutdown
 }
 
-// This example demonstrates how to use [kod.WithLogger] to provide a custom logger to the application.
-func Example_log() {
+// This example demonstrates how to use logging with OpenTelemetry.
+func Example_openTelemetryLog() {
 	logger, observer := kod.NewTestLogger()
 
 	kod.RunTest(&testing.T{}, func(ctx context.Context, app *helloworld.App) {
@@ -104,15 +104,57 @@ func Example_log() {
 		app.HelloWorld.Get().SayHello(ctx)
 	}, kod.WithLogger(logger))
 
-	fmt.Println(observer)
+	fmt.Println(observer.RemoveKeys("trace_id", "span_id", "time"))
+
+	// Output:
+	// helloWorld init
+	// Hello, World!
+	// helloWorld shutdown
+	// {"component":"github.com/go-kod/kod/Main","level":"INFO","msg":"Hello, World!"}
+	// {"component":"github.com/go-kod/kod/Main","level":"WARN","msg":"Hello, World!"}
+	// {"component":"github.com/go-kod/kod/Main","level":"ERROR","msg":"Hello, World!"}
+	// {"component":"github.com/go-kod/kod/examples/helloworld/HelloWorld","level":"INFO","msg":"Hello, World!"}
+}
+
+// This example demonstrates how to use tracing with OpenTelemetry.
+func Example_openTelemetryTrace() {
+	logger, observer := kod.NewTestLogger()
+
+	kod.Run(context.Background(), func(ctx context.Context, app *helloworld.App) error {
+		ctx, span := app.Tracer().Start(ctx, "example")
+		defer span.End()
+		app.L(ctx).Info("Hello, World!")
+		app.L(ctx).WarnContext(ctx, "Hello, World!")
+
+		app.HelloWorld.Get().SayHello(ctx)
+		return nil
+	}, kod.WithInterceptors(ktrace.Interceptor()), kod.WithLogger(logger))
+
+	fmt.Println(observer.Filter(func(m map[string]any) bool {
+		return m["trace_id"] != nil && m["span_id"] != nil
+	}).RemoveKeys("trace_id", "span_id", "time"))
+
 	// Output:
 	// helloWorld init
 	// Hello, World!
 	// helloWorld shutdown
-	// {"level":"INFO","msg":"Hello, World!","component":"github.com/go-kod/kod/Main"}
-	// {"level":"WARN","msg":"Hello, World!","component":"github.com/go-kod/kod/Main"}
-	// {"level":"ERROR","msg":"Hello, World!","component":"github.com/go-kod/kod/Main"}
-	// {"level":"INFO","msg":"Hello, World!","component":"github.com/go-kod/kod/examples/helloworld/HelloWorld"}
+	// {"component":"github.com/go-kod/kod/Main","level":"INFO","msg":"Hello, World!"}
+	// {"component":"github.com/go-kod/kod/Main","level":"WARN","msg":"Hello, World!"}
+	// {"component":"github.com/go-kod/kod/examples/helloworld/HelloWorld","level":"INFO","msg":"Hello, World!"}
+}
+
+// This example demonstrates how to use metrics with OpenTelemetry.
+func Example_openTelemetryMetric() {
+	kod.Run(context.Background(), func(ctx context.Context, app *helloworld.App) error {
+		metric, _ := app.Meter().Int64Counter("example")
+		metric.Add(ctx, 1)
+
+		return nil
+	})
+
+	// Output:
+	// helloWorld init
+	// helloWorld shutdown
 }
 
 // This example demonstrates how to use [kod.WithInterceptors] to provide a custom interceptor to the application.

internal/kslog/log_observer.go

@@ -9,14 +9,15 @@ import (
 	"github.com/samber/lo"
 )
 
-// removeTime removes the top-level time attribute.
-// It is intended to be used as a ReplaceAttr function,
-// to make example output deterministic.
-func removeTime(groups []string, a slog.Attr) slog.Attr {
-	if a.Key == slog.TimeKey && len(groups) == 0 {
-		return slog.Attr{}
+// NewTestLogger returns a new test logger.
+func NewTestLogger() (*slog.Logger, *observer) {
+	observer := &observer{
+		buf: new(bytes.Buffer),
 	}
-	return a
+	log := slog.New(slog.NewJSONHandler(observer.buf, nil))
+	slog.SetDefault(log)
+
+	return log, observer
 }
 
 type observer struct {
@@ -77,21 +78,30 @@ func (b *observer) Filter(filter func(map[string]any) bool) *observer {
 	}
 }
 
+// RemoveKeys removes the provided keys from the observed logs.
+func (b *observer) RemoveKeys(keys ...string) *observer {
+	filtered := make([]map[string]any, 0)
+	for _, line := range b.parse() {
+		for _, key := range keys {
+			delete(line, key)
+		}
+
+		filtered = append(filtered, line)
+	}
+
+	buf := new(bytes.Buffer)
+	for _, line := range filtered {
+		lo.Must0(json.NewEncoder(buf).Encode(line))
+	}
+
+	return &observer{
+		buf: buf,
+	}
+}
+
 // Clean clears the observed logs.
 func (b *observer) Clean() *observer {
 	b.buf.Reset()
 
 	return b
 }
-
-func NewTestLogger() (*slog.Logger, *observer) {
-	observer := &observer{
-		buf: new(bytes.Buffer),
-	}
-	log := slog.New(slog.NewJSONHandler(observer.buf, &slog.HandlerOptions{
-		ReplaceAttr: removeTime,
-	}))
-	slog.SetDefault(log)
-
-	return log, observer
-}

kod.go

@@ -20,12 +20,14 @@ import (
 	"go.opentelemetry.io/contrib/instrumentation/runtime"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/log/global"
+	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/sdk/log"
-	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/resource"
-	"go.opentelemetry.io/otel/sdk/trace"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+	sdkresource "go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 	semconv "go.opentelemetry.io/otel/semconv/v1.25.0"
+	"go.opentelemetry.io/otel/trace"
 
 	"github.com/go-kod/kod/interceptor"
 	"github.com/go-kod/kod/internal/hooks"
@@ -41,7 +43,8 @@ const (
 // Implements[T any] provides a common structure for components,
 // with logging capabilities and a reference to the component's interface.
 type Implements[T any] struct {
-	log *slog.Logger
+	name string
+	log  *slog.Logger
 	//nolint
 	component_interface_type T
 }
@@ -51,10 +54,21 @@ func (i *Implements[T]) L(ctx context.Context) *slog.Logger {
 	return kslog.LogWithContext(ctx, i.log)
 }
 
+// T return the associated tracer.
+func (i *Implements[T]) Tracer(opts ...trace.TracerOption) trace.Tracer {
+	return otel.Tracer(i.name, opts...)
+}
+
+// M return the associated meter.
+func (i *Implements[T]) Meter(opts ...metric.MeterOption) metric.Meter {
+	return otel.GetMeterProvider().Meter(i.name, opts...)
+}
+
 // setLogger sets the logger for the component.
 // nolint
-func (i *Implements[T]) setLogger(log *slog.Logger) {
-	i.log = log
+func (i *Implements[T]) setLogger(name string, log *slog.Logger) {
+	i.name = name
+	i.log = log.With("component", name)
 }
 
 // implements is a marker method to assert implementation of an interface.
@@ -461,11 +475,11 @@ func (k *Kod) initOpenTelemetry(ctx context.Context) {
 	lo.Must0(host.Start())
 	lo.Must0(runtime.Start())
 
-	res := lo.Must(resource.New(ctx,
-		resource.WithFromEnv(),
-		resource.WithTelemetrySDK(),
-		resource.WithHost(),
-		resource.WithAttributes(
+	res := lo.Must(sdkresource.New(ctx,
+		sdkresource.WithFromEnv(),
+		sdkresource.WithTelemetrySDK(),
+		sdkresource.WithHost(),
+		sdkresource.WithAttributes(
 			semconv.ServiceNameKey.String(k.config.Name),
 			semconv.ServiceVersionKey.String(k.config.Version),
 			semconv.DeploymentEnvironmentKey.String(k.config.Env),
@@ -478,11 +492,11 @@ func (k *Kod) initOpenTelemetry(ctx context.Context) {
 }
 
 // configureTrace configures the trace provider with the provided context and resource.
-func (k *Kod) configureTrace(ctx context.Context, res *resource.Resource) {
+func (k *Kod) configureTrace(ctx context.Context, res *sdkresource.Resource) {
 	spanExporter := lo.Must(autoexport.NewSpanExporter(ctx))
-	spanProvider := trace.NewTracerProvider(
-		trace.WithBatcher(spanExporter),
-		trace.WithResource(res),
+	spanProvider := sdktrace.NewTracerProvider(
+		sdktrace.WithBatcher(spanExporter),
+		sdktrace.WithResource(res),
 	)
 
 	otel.SetTextMapPropagator(
@@ -499,11 +513,11 @@ func (k *Kod) configureTrace(ctx context.Context, res *resource.Resource) {
 }
 
 // configureMetric configures the metric provider with the provided context and resource.
-func (k *Kod) configureMetric(ctx context.Context, res *resource.Resource) {
+func (k *Kod) configureMetric(ctx context.Context, res *sdkresource.Resource) {
 	metricReader := lo.Must(autoexport.NewMetricReader(ctx))
-	metricProvider := metric.NewMeterProvider(
-		metric.WithReader(metricReader),
-		metric.WithResource(res),
+	metricProvider := sdkmetric.NewMeterProvider(
+		sdkmetric.WithReader(metricReader),
+		sdkmetric.WithResource(res),
 	)
 
 	otel.SetMeterProvider(metricProvider)
@@ -515,7 +529,7 @@ func (k *Kod) configureMetric(ctx context.Context, res *resource.Resource) {
 }
 
 // configureLog configures the log provider with the provided context and resource.
-func (k *Kod) configureLog(ctx context.Context, res *resource.Resource) {
+func (k *Kod) configureLog(ctx context.Context, res *sdkresource.Resource) {
 	logExporter := lo.Must(autoexport.NewLogExporter(ctx))
 	loggerProvider := log.NewLoggerProvider(
 		log.WithProcessor(

registry.go

@@ -101,8 +101,7 @@ func (k *Kod) get(ctx context.Context, reg *Registration) (any, error) {
 	}
 
 	// Fill logger.
-	logger := k.log.With(slog.String("component", reg.Name))
-	if err := fillLog(obj, logger); err != nil {
+	if err := fillLog(reg.Name, obj, k.log); err != nil {
 		return nil, err
 	}
 
@@ -136,13 +135,13 @@ func (k *Kod) get(ctx context.Context, reg *Registration) (any, error) {
 	return obj, nil
 }
 
-func fillLog(obj any, log *slog.Logger) error {
-	x, ok := obj.(interface{ setLogger(*slog.Logger) })
+func fillLog(name string, obj any, log *slog.Logger) error {
+	x, ok := obj.(interface{ setLogger(string, *slog.Logger) })
 	if !ok {
 		return fmt.Errorf("fillLog: %T does not implement kod.Implements", obj)
 	}
 
-	x.setLogger(log)
+	x.setLogger(name, log)
 	return nil
 }
 

registry_test.go

@@ -13,7 +13,7 @@ import (
 
 func TestFill(t *testing.T) {
 	t.Run("case 1", func(t *testing.T) {
-		assert.NotNil(t, fillLog(nil, nil))
+		assert.NotNil(t, fillLog("", nil, nil))
 	})
 
 	t.Run("case 2", func(t *testing.T) {