Go net/http server error: accept tcp [::]:443: accept4: too many open files; retrying

Here is my server :

package main
import (
"my-project/pkg/configuration"
"my-project/pkg/logger"
"my-project/pkg/server/appConfig"
"my-project/pkg/server/handlers"
"net/http"
"os"
"strings"
)
func main() {
if len(os.Args) < 2 {
logger.Log("error", "main", "Missing config.json file path as argument")
return
}
configuration := configuration.Configuration{}
appConfig.InitConfig(os.Args[1], &configuration)
// download file
http.HandleFunc("/file-download", handlers.DownloadFile(&configuration))
// upload file
http.HandleFunc("/file-upload", handlers.UploadFile(&configuration))
// Get url
http.HandleFunc("/file-url", handlers.GetUrl(&configuration))
// Delete
http.HandleFunc("/delete", handlers.DeleteHandler(&configuration))
// file system
fs := http.FileServer(http.Dir(configuration.RootStoragePath))
corsFS := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if strings.HasSuffix(r.URL.Path, "/") {
http.NotFound(w, r)
return
}
w.Header().Add("Access-Control-Allow-Origin", "*")
fs.ServeHTTP(w, r)
})
http.Handle("/", corsFS)
err := http.ListenAndServeTLS(":443", "crt/server.crt", "crt/server.key", nil)
if err != nil {
logger.Log("error", "ListenAndServeTLS", err.Error())
}
}

The server is under medium load.
The server crashed after a day of running,
I got the following error:

http: Accept error: accept tcp [::]:443: accept4: too many open files; retrying

The command :

ls -ltr /proc/{PROCESS_ID}/fd

And the list of file, and socket:[XXXXXX] is growing all the time.
I don't want to change ulimit (1024), I don't think it is a long terme fix...

I don't really see where the problem could come from... In the handlers, I manipulate files but I take care to do defer Close()...
Do I have to set timeouts? If so where?

Thank you in advance for all the help ...

I finally managed to find a solution.

The fact is that the http.ListenAndServe method of the net/http package has no timeout by default. This is voluntary from the Go team. So for a service in production, it is necessary to declare a http.Server{} and to configure it. Go doc.
Source : Cloudflare blog post

        srv := &http.Server{
Addr:         ":443",
ReadTimeout:  30 * time.Second,
WriteTimeout: 120 * time.Second,
}   
srv.SetKeepAlivesEnabled(false)
err := srv.ListenAndServeTLS("crt/server.crt", "crt/server.key")

http.DefaultServeMux is the default request multiplexer, and HandleFunc registers the handler function for the given pattern in the DefaultServeMux.
Here is the implementation :

func main() {
if len(os.Args) < 2 { 
logger.Log("error", "main", "Missing config.json file path as argument")
return
}
configuration := configuration.Configuration{}
appConfig.InitConfig(os.Args[1], &configuration)
// download file
http.HandleFunc("/file-download", handlers.DownloadFile(&configuration))
// upload file
http.HandleFunc("/file-upload", handlers.UploadFile(&configuration))
// Get url
http.HandleFunc("/file-url", handlers.GetUrl(&configuration))
// Delete
http.HandleFunc("/delete", handlers.DeleteHandler(&configuration))
// file system
fs := http.FileServer(http.Dir(configuration.RootStoragePath))
corsFS := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if strings.HasSuffix(r.URL.Path, "/") {
http.NotFound(w, r)
return
}   
w.Header().Add("Access-Control-Allow-Origin", "*")
fs.ServeHTTP(w, r)
})
http.Handle("/", corsFS)
srv := &http.Server{
Addr:         ":443",
ReadTimeout:  30 * time.Second,
WriteTimeout: 120 * time.Second,
}   
srv.SetKeepAlivesEnabled(false)
err := srv.ListenAndServeTLS("crt/server.crt", "crt/server.key")
if err != nil {
logger.Log("error", "ListenAndServeTLS", err.Error())
os.Exit(1)
}
}

If you have any other advice, I'm obviously interested.