simple_http_server.go

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
)

func main() {
	port := os.Getenv("PORT")
	if len(port) == 0 {
		log.Fatalf("PORT environment not set")
	}

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(200)
		fmt.Fprintf(w, "Hello World")
	})

	addr := fmt.Sprintf(":%s", os.Getenv("PORT"))
	s := http.Server{Addr: addr}

	go (func() {
		log.Fatal(s.ListenAndServe())
	})()

	log.Printf("Server is up and running at address '%s'", addr)

	signalChan := make(chan os.Signal, 1)
	signal.Notify(signalChan, syscall.SIGINT, syscall.SIGTERM)
	<-signalChan

	log.Printf("Shutdown signal received, exiting...")

	s.Shutdown(context.Background())
}