Add logs to dice example (#5349)

* Add logs to dice example

Use slog to log a message on the server handler.

* Add changelog entry

* Split impl for 1.22 and 1.21

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add `RecordFactory` in `go.opentelemetry.io/otel/sdk/log/logtest` to facilitate testing the exporter and processor implementations. (#5258)
 - Add example for `go.opentelemetry.io/otel/exporters/stdout/stdoutlog`. (#5242)
 - The count of dropped records from the `BatchProcessor` in `go.opentelemetry.io/otel/sdk/log` is logged. (#5276)
+- Add logs to `go.opentelemetry.io/otel/example/dice`. (#5349)
 
 ### Changed
 

example/dice/go.mod

@@ -3,12 +3,16 @@ module go.opentelemetry.io/otel/example/dice
 go 1.21
 
 require (
+	go.opentelemetry.io/contrib/bridges/otelslog v0.1.0
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.51.0
 	go.opentelemetry.io/otel v1.26.0
+	go.opentelemetry.io/otel/exporters/stdout/stdoutlog v0.2.0-alpha
 	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.26.0
 	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.26.0
+	go.opentelemetry.io/otel/log v0.2.0-alpha
 	go.opentelemetry.io/otel/metric v1.26.0
 	go.opentelemetry.io/otel/sdk v1.26.0
+	go.opentelemetry.io/otel/sdk/log v0.2.0-alpha
 	go.opentelemetry.io/otel/sdk/metric v1.26.0
 )
 
@@ -33,3 +37,9 @@ replace go.opentelemetry.io/otel/metric => ../../metric
 replace go.opentelemetry.io/otel/sdk/metric => ../../sdk/metric
 
 replace go.opentelemetry.io/otel/sdk => ../../sdk
+
+replace go.opentelemetry.io/otel/exporters/stdout/stdoutlog => ../../exporters/stdout/stdoutlog
+
+replace go.opentelemetry.io/otel/log => ../../log
+
+replace go.opentelemetry.io/otel/sdk/log => ../../sdk/log

example/dice/go.sum

@@ -13,6 +13,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+go.opentelemetry.io/contrib/bridges/otelslog v0.1.0 h1:XQka5HbIS6JOeZvWz3oKyvzGmMaw7bsHH6r26Kmbrc4=
+go.opentelemetry.io/contrib/bridges/otelslog v0.1.0/go.mod h1:TTRD9H+Ddlxv9NaX+2kQXUGiYAOpcOS0kkTlC1EI4Wg=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.51.0 h1:Xs2Ncz0gNihqu9iosIZ5SkBbWo5T8JhhLJFMQL1qmLI=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.51.0/go.mod h1:vy+2G/6NvVMpwGX/NyLqcC41fxepnuKHk16E6IZUcJc=
 golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=

example/dice/main.go

@@ -78,7 +78,8 @@ func newHTTPHandler() http.Handler {
 	}
 
 	// Register handlers.
-	handleFunc("/rolldice", rolldice)
+	handleFunc("/rolldice/", rolldice)
+	handleFunc("/rolldice/{player}", rolldice)
 
 	// Add HTTP instrumentation for the whole server.
 	handler := otelhttp.NewHandler(mux, "/")

example/dice/otel.go

@@ -9,9 +9,12 @@ import (
 	"time"
 
 	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutlog"
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
+	"go.opentelemetry.io/otel/log/global"
 	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/log"
 	"go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/trace"
 )
@@ -60,6 +63,15 @@ func setupOTelSDK(ctx context.Context) (shutdown func(context.Context) error, er
 	shutdownFuncs = append(shutdownFuncs, meterProvider.Shutdown)
 	otel.SetMeterProvider(meterProvider)
 
+	// Set up logger provider.
+	loggerProvider, err := newLoggerProvider()
+	if err != nil {
+		handleErr(err)
+		return
+	}
+	shutdownFuncs = append(shutdownFuncs, loggerProvider.Shutdown)
+	global.SetLoggerProvider(loggerProvider)
+
 	return
 }
 
@@ -98,3 +110,15 @@ func newMeterProvider() (*metric.MeterProvider, error) {
 	)
 	return meterProvider, nil
 }
+
+func newLoggerProvider() (*log.LoggerProvider, error) {
+	logExporter, err := stdoutlog.New()
+	if err != nil {
+		return nil, err
+	}
+
+	meterProvider := log.NewLoggerProvider(
+		log.WithProcessor(log.NewBatchProcessor(logExporter)),
+	)
+	return meterProvider, nil
+}

example/dice/rolldice.go

@@ -4,20 +4,22 @@
 package main
 
 import (
-	"io"
-	"log"
-	"math/rand"
-	"net/http"
-	"strconv"
-
+	"go.opentelemetry.io/contrib/bridges/otelslog"
 	"go.opentelemetry.io/otel"
-	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
 )
 
+const name = "rolldice"
+
 var (
-	tracer  = otel.Tracer("rolldice")
-	meter   = otel.Meter("rolldice")
+	tracer = otel.Tracer(name)
+	meter  = otel.Meter(name)
+	logger = otelslog.NewLogger(
+		otelslog.WithInstrumentationScope(instrumentation.Scope{
+			Name: name,
+		}),
+	)
 	rollCnt metric.Int64Counter
 )
 
@@ -30,19 +32,3 @@ func init() {
 		panic(err)
 	}
 }
-
-func rolldice(w http.ResponseWriter, r *http.Request) {
-	ctx, span := tracer.Start(r.Context(), "roll")
-	defer span.End()
-
-	roll := 1 + rand.Intn(6)
-
-	rollValueAttr := attribute.Int("roll.value", roll)
-	span.SetAttributes(rollValueAttr)
-	rollCnt.Add(ctx, 1, metric.WithAttributes(rollValueAttr))
-
-	resp := strconv.Itoa(roll) + "\n"
-	if _, err := io.WriteString(w, resp); err != nil {
-		log.Printf("Write failed: %v\n", err)
-	}
-}

example/dice/rolldice_go1.21.go

@@ -0,0 +1,35 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build !go1.22
+// +build !go1.22
+
+package main
+
+import (
+	"io"
+	"math/rand"
+	"net/http"
+	"strconv"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+)
+
+func rolldice(w http.ResponseWriter, r *http.Request) {
+	ctx, span := tracer.Start(r.Context(), "roll")
+	defer span.End()
+
+	roll := 1 + rand.Intn(6)
+
+	logger.InfoContext(ctx, "Anonymous player is rolling the dice", "result", roll)
+
+	rollValueAttr := attribute.Int("roll.value", roll)
+	span.SetAttributes(rollValueAttr)
+	rollCnt.Add(ctx, 1, metric.WithAttributes(rollValueAttr))
+
+	resp := strconv.Itoa(roll) + "\n"
+	if _, err := io.WriteString(w, resp); err != nil {
+		logger.ErrorContext(ctx, "Write failed", "error", err)
+	}
+}

example/dice/rolldice_go1.22.go

@@ -0,0 +1,42 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build go1.22
+// +build go1.22
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"math/rand"
+	"net/http"
+	"strconv"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+)
+
+func rolldice(w http.ResponseWriter, r *http.Request) {
+	ctx, span := tracer.Start(r.Context(), "roll")
+	defer span.End()
+
+	roll := 1 + rand.Intn(6)
+
+	var msg string
+	if player := r.PathValue("player"); player != "" {
+		msg = fmt.Sprintf("%s is rolling the dice", player)
+	} else {
+		msg = "Anonymous player is rolling the dice"
+	}
+	logger.InfoContext(ctx, msg, "result", roll)
+
+	rollValueAttr := attribute.Int("roll.value", roll)
+	span.SetAttributes(rollValueAttr)
+	rollCnt.Add(ctx, 1, metric.WithAttributes(rollValueAttr))
+
+	resp := strconv.Itoa(roll) + "\n"
+	if _, err := io.WriteString(w, resp); err != nil {
+		logger.ErrorContext(ctx, "Write failed", "error", err)
+	}
+}