contrib: add log/slog instrumentation (#2765)

contrib/log/slog/example_test.go

@@ -0,0 +1,48 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+package slog_test
+
+import (
+	"context"
+	"log/slog"
+	"os"
+
+	slogtrace "gopkg.in/DataDog/dd-trace-go.v1/contrib/log/slog"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
+)
+
+func ExampleNewJSONHandler() {
+	// start the DataDog tracer
+	tracer.Start()
+	defer tracer.Stop()
+
+	// create the application logger
+	logger := slog.New(slogtrace.NewJSONHandler(os.Stdout, nil))
+
+	// start a new span
+	span, ctx := tracer.StartSpanFromContext(context.Background(), "ExampleNewJSONHandler")
+	defer span.Finish()
+
+	// log a message using the context containing span information
+	logger.Log(ctx, slog.LevelInfo, "this is a log with tracing information")
+}
+
+func ExampleWrapHandler() {
+	// start the DataDog tracer
+	tracer.Start()
+	defer tracer.Stop()
+
+	// create the application logger
+	myHandler := slog.NewJSONHandler(os.Stdout, nil)
+	logger := slog.New(slogtrace.WrapHandler(myHandler))
+
+	// start a new span
+	span, ctx := tracer.StartSpanFromContext(context.Background(), "ExampleWrapHandler")
+	defer span.Finish()
+
+	// log a message using the context containing span information
+	logger.Log(ctx, slog.LevelInfo, "this is a log with tracing information")
+}

contrib/log/slog/slog.go

@@ -0,0 +1,51 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+// Package slog provides functions to correlate logs and traces using log/slog package (https://pkg.go.dev/log/slog).
+package slog // import "gopkg.in/DataDog/dd-trace-go.v1/contrib/log/slog"
+
+import (
+	"context"
+	"io"
+	"log/slog"
+
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/telemetry"
+)
+
+const componentName = "log/slog"
+
+func init() {
+	telemetry.LoadIntegration(componentName)
+	tracer.MarkIntegrationImported("log/slog")
+}
+
+// NewJSONHandler is a convenience function that returns a *slog.JSONHandler logger enhanced with
+// tracing information.
+func NewJSONHandler(w io.Writer, opts *slog.HandlerOptions) slog.Handler {
+	return WrapHandler(slog.NewJSONHandler(w, opts))
+}
+
+// WrapHandler enhances the given logger handler attaching tracing information to logs.
+func WrapHandler(h slog.Handler) slog.Handler {
+	return &handler{h}
+}
+
+type handler struct {
+	slog.Handler
+}
+
+// Handle handles the given Record, attaching tracing information if found.
+func (h *handler) Handle(ctx context.Context, rec slog.Record) error {
+	span, ok := tracer.SpanFromContext(ctx)
+	if ok {
+		rec.Add(
+			slog.Uint64(ext.LogKeyTraceID, span.Context().TraceID()),
+			slog.Uint64(ext.LogKeySpanID, span.Context().SpanID()),
+		)
+	}
+	return h.Handler.Handle(ctx, rec)
+}

contrib/log/slog/slog_test.go

@@ -0,0 +1,76 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+package slog
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"log/slog"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
+	internallog "gopkg.in/DataDog/dd-trace-go.v1/internal/log"
+)
+
+func assertLogEntry(t *testing.T, rawEntry, wantMsg, wantLevel string) {
+	t.Helper()
+
+	var data map[string]interface{}
+	err := json.Unmarshal([]byte(rawEntry), &data)
+	require.NoError(t, err)
+	require.NotEmpty(t, data)
+
+	assert.Equal(t, wantMsg, data["msg"])
+	assert.Equal(t, wantLevel, data["level"])
+	assert.NotEmpty(t, data["time"])
+	assert.NotEmpty(t, data[ext.LogKeyTraceID])
+	assert.NotEmpty(t, data[ext.LogKeySpanID])
+}
+
+func testLogger(t *testing.T, createHandler func(b *bytes.Buffer) slog.Handler) {
+	tracer.Start(tracer.WithLogger(internallog.DiscardLogger{}))
+	defer tracer.Stop()
+
+	// create the application logger
+	var b bytes.Buffer
+	h := createHandler(&b)
+	logger := slog.New(h)
+
+	// start a new span
+	span, ctx := tracer.StartSpanFromContext(context.Background(), "test")
+	defer span.Finish()
+
+	// log a message using the context containing span information
+	logger.Log(ctx, slog.LevelInfo, "this is an info log with tracing information")
+	logger.Log(ctx, slog.LevelError, "this is an error log with tracing information")
+
+	logs := strings.Split(
+		strings.TrimRight(b.String(), "\n"),
+		"\n",
+	)
+	// assert log entries contain trace information
+	require.Len(t, logs, 2)
+	assertLogEntry(t, logs[0], "this is an info log with tracing information", "INFO")
+	assertLogEntry(t, logs[1], "this is an error log with tracing information", "ERROR")
+}
+
+func TestNewJSONHandler(t *testing.T) {
+	testLogger(t, func(b *bytes.Buffer) slog.Handler {
+		return NewJSONHandler(b, nil)
+	})
+}
+
+func TestWrapHandler(t *testing.T) {
+	testLogger(t, func(b *bytes.Buffer) slog.Handler {
+		return WrapHandler(slog.NewJSONHandler(b, nil))
+	})
+}

contrib/sirupsen/logrus/logrus.go

@@ -7,6 +7,7 @@
 package logrus
 
 import (
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
 	"gopkg.in/DataDog/dd-trace-go.v1/internal/telemetry"
 
@@ -34,7 +35,7 @@ func (d *DDContextLogHook) Fire(e *logrus.Entry) error {
 	if !found {
 		return nil
 	}
-	e.Data["dd.trace_id"] = span.Context().TraceID()
-	e.Data["dd.span_id"] = span.Context().SpanID()
+	e.Data[ext.LogKeyTraceID] = span.Context().TraceID()
+	e.Data[ext.LogKeySpanID] = span.Context().SpanID()
 	return nil
 }

ddtrace/ext/log_key.go

@@ -0,0 +1,13 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+package ext
+
+const (
+	// LogKeyTraceID is used by log integrations to correlate logs with a given trace.
+	LogKeyTraceID = "dd.trace_id"
+	// LogKeySpanID is used by log integrations to correlate logs with a given span.
+	LogKeySpanID = "dd.span_id"
+)

ddtrace/tracer/option.go

@@ -95,6 +95,7 @@ var contribIntegrations = map[string]struct {
 	"github.com/urfave/negroni":                     {"Negroni", false},
 	"github.com/valyala/fasthttp":                   {"FastHTTP", false},
 	"github.com/zenazn/goji":                        {"Goji", false},
+	"log/slog":                                      {"log/slog", false},
 }
 
 var (

ddtrace/tracer/option_test.go

@@ -255,7 +255,7 @@ func TestAgentIntegration(t *testing.T) {
 		defer clearIntegrationsForTests()
 
 		cfg.loadContribIntegrations(nil)
-		assert.Equal(t, len(cfg.integrations), 55)
+		assert.Equal(t, 56, len(cfg.integrations))
 		for integrationName, v := range cfg.integrations {
 			assert.False(t, v.Instrumented, "integrationName=%s", integrationName)
 		}