How to Create http NewServeMux and run with go routine? - go

Question

I have an issue about http.NewServeMux, I've tried to run with go routine but it's doesn't work.
package main
import (
"context"
"fmt"
"log"
"net/http"
"os"
"os/signal"
"syscall"
"time"
)
func run() (s *http.Server) {
mux := http.NewServeMux()
mux.HandleFunc("/", func(rw http.ResponseWriter, r *http.Request) {
rw.WriteHeader(http.StatusOK)
fmt.Fprint(rw, "under construction")
})
s = &http.Server{
Addr: ":8080",
ReadTimeout: 10 * time.Second,
WriteTimeout: 10 * time.Second,
MaxHeaderBytes: 1 << 20,
}
go func() {
if err := s.ListenAndServe(); err != nil && err != http.ErrServerClosed {
log.Fatalf("listen: %s\n", err)
}
}()
return
}
func main() {
s := run()
quit := make(chan os.Signal)
signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
<-quit
log.Println("Shutting down server...")
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer func() {
cancel()
}()
if err := s.Shutdown(ctx); err != nil {
log.Fatal("Server forced to shutdown")
}
log.Println("Server exiting")
}
then run with
go run main.go
And access to http://localhost:8080/ that's always to get.
404 page not found
How I can solve this issue?

Answer 1

This is because you're setting up mux but never do anything with it:
// mux is never referenced after you add the default handler
mux := http.NewServeMux()
mux.HandleFunc("/", func(rw http.ResponseWriter, r *http.Request) {
rw.WriteHeader(http.StatusOK)
fmt.Fprint(rw, "under construction")
})
Change your handler to use your mux var instead of http.DefaultServeMux and everything works as expected:
s = &http.Server{
Handler: mux, // This is the important line
Addr: ":8080",
ReadTimeout: 10 * time.Second,
WriteTimeout: 10 * time.Second,
MaxHeaderBytes: 1 << 20,
}