otelgin: add routeName argument to SpanNameFormatter function

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
   For example, `[]string{"foo", "bar"}` attribute value is now transformed to `log.SliceValue(log.StringValue("foo"), log.StringValue("bar"))` instead of `log.String("[foo bar"])`. (#6254)
 - Add the `WithSource` option to the `go.opentelemetry.io/contrib/bridges/otelslog` log bridge to set the `code.*` attributes in the log record that includes the source location where the record was emitted. (#6253)
 - Add `ContextWithStartTime` and `StartTimeFromContext` to `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp`, which allows setting the start time using go context. (#6137)
+- Add `routeName` argument to `SpanNameFormatter` function in `go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin`. (#5741)
 
 ### Fixed
 

instrumentation/github.com/gin-gonic/gin/otelgin/gintrace.go

@@ -75,7 +75,7 @@ func Middleware(service string, opts ...Option) gin.HandlerFunc {
 		if cfg.SpanNameFormatter == nil {
 			spanName = c.FullPath()
 		} else {
-			spanName = cfg.SpanNameFormatter(c.Request)
+			spanName = cfg.SpanNameFormatter(c.FullPath(), c.Request)
 		}
 		if spanName == "" {
 			spanName = fmt.Sprintf("HTTP %s route not found", c.Request.Method)

instrumentation/github.com/gin-gonic/gin/otelgin/option.go

@@ -30,8 +30,8 @@ type Filter func(*http.Request) bool
 // gin.Context has FullPath() method, which returns a matched route full path.
 type GinFilter func(*gin.Context) bool
 
-// SpanNameFormatter is used to set span name by http.request.
-type SpanNameFormatter func(r *http.Request) string
+// SpanNameFormatter is used to set span name by http.Request.
+type SpanNameFormatter func(routeName string, r *http.Request) string
 
 // Option specifies instrumentation configuration options.
 type Option interface {
@@ -84,9 +84,11 @@ func WithGinFilter(f ...GinFilter) Option {
 	})
 }
 
-// WithSpanNameFormatter takes a function that will be called on every
-// request and the returned string will become the Span Name.
-func WithSpanNameFormatter(f func(r *http.Request) string) Option {
+// WithSpanNameFormatter specifies a function to use for generating a custom span
+// name. By default, the route name (path template or regexp) is used. The route
+// name is provided so you can use it in the span name without needing to
+// duplicate the logic for extracting it from the request.
+func WithSpanNameFormatter(f func(routeName string, r *http.Request) string) Option {
 	return optionFunc(func(c *config) {
 		c.SpanNameFormatter = f
 	})

instrumentation/github.com/gin-gonic/gin/otelgin/test/gintrace_test.go

@@ -7,6 +7,7 @@ package test
 
 import (
 	"errors"
+	"fmt"
 	"html/template"
 	"net/http"
 	"net/http/httptest"
@@ -160,7 +161,8 @@ func TestSpanName(t *testing.T) {
 		wantSpanName      string
 	}{
 		{"/user/1", nil, "/user/:id"},
-		{"/user/1", func(r *http.Request) string { return r.URL.Path }, "/user/1"},
+		{"/user/1", func(routeName string, r *http.Request) string { return r.URL.Path }, "/user/1"},
+		{"/user/1", func(routeName string, r *http.Request) string { return fmt.Sprintf("%s %s", r.Method, routeName) }, "GET /user/:id"},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.requestPath, func(t *testing.T) {
@@ -171,7 +173,7 @@ func TestSpanName(t *testing.T) {
 			router.Use(otelgin.Middleware("foobar", otelgin.WithTracerProvider(provider), otelgin.WithSpanNameFormatter(tc.spanNameFormatter)))
 			router.GET("/user/:id", func(c *gin.Context) {})
 
-			router.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest("GET", tc.requestPath, nil))
+			router.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest(http.MethodGet, tc.requestPath, nil))
 
 			require.Len(t, sr.Ended(), 1, "should emit a span")
 			assert.Equal(t, tc.wantSpanName, sr.Ended()[0].Name(), "span name not correct")
@@ -186,8 +188,8 @@ func TestHTTPRouteWithSpanNameFormatter(t *testing.T) {
 	router := gin.New()
 	router.Use(otelgin.Middleware("foobar",
 		otelgin.WithTracerProvider(provider),
-		otelgin.WithSpanNameFormatter(func(r *http.Request) string {
-			return r.URL.Path
+		otelgin.WithSpanNameFormatter(func(routeName string, r *http.Request) string {
+			return fmt.Sprintf("%s %s", r.Method, routeName)
 		}),
 	),
 	)
@@ -208,7 +210,7 @@ func TestHTTPRouteWithSpanNameFormatter(t *testing.T) {
 	spans := sr.Ended()
 	require.Len(t, spans, 1)
 	span := spans[0]
-	assert.Equal(t, "/user/123", span.Name())
+	assert.Equal(t, "GET /user/:id", span.Name())
 	assert.Equal(t, oteltrace.SpanKindServer, span.SpanKind())
 	attr := span.Attributes()
 	assert.Contains(t, attr, attribute.String("http.method", "GET"))