Add Custom Attributes does not work

[mybigman]

Has no effect at all.

Looking at it its creating a new request however the middleware doesn't see that request.

[samber]

Can you make a short demo of the issue please ?

It works in the example provided in the repository.

[alessio-perugini]

@samber I'm having the same problem. I discovered that it depends on the order of some middleware I use. Below you can find a minimal example that reproduces the problem:

package main

import (
	"net/http"

	"log/slog"

	sloghttp "github.com/samber/slog-http"
	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
)

func main() {
	mux := http.NewServeMux()

	mux.Handle("/foobar/42", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		sloghttp.AddCustomAttributes(r, slog.String("foo", "bar"))
		w.Write([]byte("Hello, World!"))
	}))

	handler := otelhttp.NewMiddleware("asd")(mux)
	handler = sloghttp.New(slog.Default().WithGroup("http"))(handler)

	http.ListenAndServe(":4242", handler)
}