server4.go

func main() {
  // STEP 1, STEP 2, STEP 3
  // ... 
  
  // Start the server in a child routine
	go func() {
		if err := s.Serve(listener); err != nil {
			log.Fatalf("Failed to serve: %v", err)
		}
	}()
	fmt.Println("Server succesfully started on port :50051")

	// Right way to stop the server using a SHUTDOWN HOOK
	// Create a channel to receive OS signals
	c := make(chan os.Signal)

	// Relay os.Interrupt to our channel (os.Interrupt = CTRL+C)
	// Ignore other incoming signals
	signal.Notify(c, os.Interrupt)

	// Block main routine until a signal is received
	// As long as user doesn't press CTRL+C a message is not passed and our main routine keeps running
	<-c

	// After receiving CTRL+C Properly stop the server
	fmt.Println("\nStopping the server...")
	s.Stop()
	listener.Close()
	fmt.Println("Closing MongoDB connection")
	db.Disconnect(mongoCtx)
	fmt.Println("Done.")
}