otelhttp: deprecate the WithRouteTag option

CHANGELOG.md

@@ -22,6 +22,12 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - Improve performance by reducing allocations in the gRPC stats handler in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#8035)
 
+### Deprecated
+
+- `WithRouteTag` in `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp` is deprecated.
+  The route is already added automatically for spans.
+  For metrics, the alternative is to use the `WithMetricAttributesFn` option. (#8117)
+
 ### Removed
 
 - Drop support for [Go 1.23]. (#7831)

examples/dice/instrumented/main.go

@@ -71,17 +71,9 @@ func run() error {
 func newHTTPHandler() http.Handler {
 	mux := http.NewServeMux()
 
-	// handleFunc is a replacement for mux.HandleFunc
-	// which enriches the handler's HTTP instrumentation with the pattern as the http.route.
-	handleFunc := func(pattern string, handlerFunc func(http.ResponseWriter, *http.Request)) {
-		// Configure the "http.route" for the HTTP instrumentation.
-		handler := otelhttp.WithRouteTag(pattern, http.HandlerFunc(handlerFunc))
-		mux.Handle(pattern, handler)
-	}
-
 	// Register handlers.
-	handleFunc("/rolldice/", rolldice)
-	handleFunc("/rolldice/{player}", rolldice)
+	mux.Handle("/rolldice", http.HandlerFunc(rolldice))
+	mux.Handle("/rolldice/{player}", http.HandlerFunc(rolldice))
 
 	// Add HTTP instrumentation for the whole server.
 	handler := otelhttp.NewHandler(mux, "/")

instrumentation/net/http/otelhttp/doc.go

@@ -2,6 +2,5 @@
 // SPDX-License-Identifier: Apache-2.0
 
 // Package otelhttp provides an http.Handler and functions that are intended
-// to be used to add tracing by wrapping existing handlers (with Handler) and
-// routes WithRouteTag.
+// to be used to add tracing by wrapping existing handlers.
 package otelhttp // import "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"

instrumentation/net/http/otelhttp/handler.go

@@ -224,6 +224,9 @@ func (h *middleware) metricAttributesFromRequest(r *http.Request) []attribute.Ke
 
 // WithRouteTag annotates spans and metrics with the provided route name
 // with HTTP route attribute.
+//
+// Deprecated: spans are automatically annotated with the route attribute.
+// To annotate metrics, use the `WithMetricAttributesFn` option.
 func WithRouteTag(route string, h http.Handler) http.Handler {
 	attr := semconv.NewHTTPServer(nil).Route(route)
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

instrumentation/net/http/otelhttp/handler_example_test.go

@@ -44,43 +44,41 @@ func ExampleNewHandler() {
 	}
 
 	var mux http.ServeMux
-	mux.Handle("/hello/",
-		otelhttp.WithRouteTag("/hello/:name", http.HandlerFunc(
-			func(w http.ResponseWriter, r *http.Request) {
-				ctx := r.Context()
-				labeler, _ := otelhttp.LabelerFromContext(ctx)
+	mux.Handle("/hello/", http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			ctx := r.Context()
+			labeler, _ := otelhttp.LabelerFromContext(ctx)
 
-				var name string
-				// Wrap another function in its own span
-				if err := func(ctx context.Context) error {
-					ctx, span := trace.SpanFromContext(ctx).TracerProvider().Tracer("exampleTracer").Start(ctx, "figureOutName")
-					defer span.End()
+			var name string
+			// Wrap another function in its own span
+			if err := func(ctx context.Context) error {
+				ctx, span := trace.SpanFromContext(ctx).TracerProvider().Tracer("exampleTracer").Start(ctx, "figureOutName")
+				defer span.End()
 
-					var err error
-					name, err = figureOutName(ctx, r.URL.Path[1:])
-					return err
-				}(ctx); err != nil {
-					log.Println("error figuring out name: ", err)
-					http.Error(w, err.Error(), http.StatusInternalServerError)
-					labeler.Add(attribute.Bool("error", true))
-					return
-				}
+				var err error
+				name, err = figureOutName(ctx, r.URL.Path[1:])
+				return err
+			}(ctx); err != nil {
+				log.Println("error figuring out name: ", err)
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				labeler.Add(attribute.Bool("error", true))
+				return
+			}
 
-				d, err := io.ReadAll(r.Body)
-				if err != nil {
-					log.Println("error reading body: ", err)
-					w.WriteHeader(http.StatusBadRequest)
-					labeler.Add(attribute.Bool("error", true))
-					return
-				}
+			d, err := io.ReadAll(r.Body)
+			if err != nil {
+				log.Println("error reading body: ", err)
+				w.WriteHeader(http.StatusBadRequest)
+				labeler.Add(attribute.Bool("error", true))
+				return
+			}
 
-				n, err := io.WriteString(w, "Hello, "+name+"!\nYou sent me this:\n"+string(d))
-				if err != nil {
-					log.Printf("error writing reply after %d bytes: %s", n, err)
-					labeler.Add(attribute.Bool("error", true))
-				}
-			}),
-		),
+			n, err := io.WriteString(w, "Hello, "+name+"!\nYou sent me this:\n"+string(d))
+			if err != nil {
+				log.Printf("error writing reply after %d bytes: %s", n, err)
+				labeler.Add(attribute.Bool("error", true))
+			}
+		}),
 	)
 
 	if err := http.ListenAndServe(":7777",