package main import ( "fmt" "log" "net/http" "os" "strconv" "github.com/go-chi/chi" ) func main() { router := chi.NewRouter() router.Get("/", func(w http.ResponseWriter, r *http.Request) { w.Write([]byte("Hello world")) }) var port int var err error port_str, exists := os.LookupEnv("WEB_SERVER_PORT") if exists { port, err = strconv.Atoi(port_str) if err != nil { log.Fatal("env:MAIL_SERVER_PORT is not a number") } } else { port = 3000 } log.Println("Listening on port", port) http.ListenAndServe(fmt.Sprintf(":%d", port), router) }