main.go

package main

import (
	"log"
	"net/http"
)

// go run main.go
//
// $ curl "http://127.0.0.1:8090"
// hello on port: 8090
//
// $ curl "http://127.0.0.1:8091"
// hello on port: 8091

func main() {
	go runServer("8090")
	go runServer("8091")

	select {}
}

type helloHandler struct {
	foo string
}

func (h helloHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("hello on port: " + h.foo))
}

// func helloHandler(w http.ResponseWriter, r *http.Request) {
// 	w.Write([]byte("hello"))
// }

func runServer(port string) {
	// "panic: http: multiple registrations for /"
	// http.HandleFunc("/", helloHandler)
	// http.ListenAndServe(host+":"+port, nil)

	mux := http.NewServeMux()

	helloSrv := helloHandler{foo: port}
	mux.Handle("/", helloSrv)

	log.Println("Listening... on port: " + port)
	http.ListenAndServe(":"+port, mux)
}