contrib/net/http: honor WithHeaderTags in WrapHandler (#2288)

Co-authored-by: Dario Castañé <[email protected]>

contrib/net/http/http.go

@@ -85,8 +85,9 @@ func WrapHandler(h http.Handler, service, resource string, opts ...Option) http.
 		if r := cfg.resourceNamer(req); r != "" {
 			resc = r
 		}
-		so := make([]ddtrace.StartSpanOption, len(cfg.spanOpts))
+		so := make([]ddtrace.StartSpanOption, len(cfg.spanOpts), len(cfg.spanOpts)+1)
 		copy(so, cfg.spanOpts)
+		so = append(so, httptrace.HeaderTagsFromRequest(req, cfg.headerTags))
 		TraceAndServe(h, w, req, &ServeConfig{
 			Service:    service,
 			Resource:   resc,

contrib/net/http/http_test.go

@@ -104,6 +104,41 @@ func TestWithHeaderTags(t *testing.T) {
 		assert.NotContains(s.Tags(), "http.headers.x-datadog-header")
 		assert.NotContains(s.Tags(), globalT)
 	})
+
+	t.Run("wrap-handler", func(t *testing.T) {
+		mt := mocktracer.Start()
+		defer mt.Stop()
+		htArgs := []string{"[email protected]*r", "2header", "3header"}
+
+		handler := WrapHandler(http.HandlerFunc(handler200), "my-service", "my-resource",
+			WithHeaderTags(htArgs),
+		)
+
+		url := "/"
+		r := httptest.NewRequest("GET", url, nil)
+		r.Header.Set("[email protected]*r", "val")
+		r.Header.Add("[email protected]*r", "val2")
+		r.Header.Set("2header", "2val")
+		r.Header.Set("3header", "3val")
+		r.Header.Set("x-datadog-header", "value")
+		w := httptest.NewRecorder()
+		handler.ServeHTTP(w, r)
+
+		assert := assert.New(t)
+		assert.Equal(200, w.Code)
+		assert.Equal("OK\n", w.Body.String())
+
+		spans := mt.FinishedSpans()
+		assert.Equal(1, len(spans))
+
+		s := spans[0]
+		assert.Equal("http.request", s.OperationName())
+
+		for _, arg := range htArgs {
+			header, tag := normalizer.HeaderTag(arg)
+			assert.Equal(strings.Join(r.Header.Values(header), ","), s.Tags()[tag])
+		}
+	})
 }
 
 func TestHttpTracer200(t *testing.T) {