show code golang GRPC use SSL - Server

server.go

package main

import (
	"calculator/calculatorpb"
	"context"
	"fmt"
	"google.golang.org/grpc/credentials"
	"io"
	"log"
	"math"
	"net"
	"os"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/reflection"
	"google.golang.org/grpc/status"
)

type server struct{}

// sum này lấy ở dòng 431 CalculatorServiceServer file calculator.pb.go
/**
Nếu bạn để ntn
func (*server) Sum(ctx context.Context, in *calculatorpb.SumRequest, opts ...grpc.CallOption)
thì dòng 39 sẽ bị lỗi calculatorpb.RegisterCalculatorServiceServer(s, &server{}) ở chỗ &server{}
*/
func (*server) Sum(ctx context.Context, req *calculatorpb.SumRequest) (*calculatorpb.SumResponse, error) {
	log.Println("sum called ..")
	resp := &calculatorpb.SumResponse{
		Result: req.GetNum1() + req.GetNum2(),
	}

	return resp, nil
}

func init() {
	os.Setenv("HOST_SERVER_NAME", "0.0.0.0")
	os.Setenv("PORT_SERVER_NAME", "50069")
}

func main() {

	//tạo 1 listener với port 50069
	bindingGrpcPort := os.Getenv("HOST_SERVER_NAME") + ":" + os.Getenv("PORT_SERVER_NAME")
	lis, err := net.Listen("tcp", bindingGrpcPort) // mở port server
	if err != nil {
		log.Fatalf("error while create listen %v", err)
	}

	//config ssl
	certFile := "ssl/server.crt"
	keyFile := "ssl/server.key"
	creds, sslErr := credentials.NewServerTLSFromFile(certFile, keyFile)
	if sslErr != nil {
		log.Fatalf("create creds ssl err %v\n", sslErr)
		return
	}
	opts := grpc.Creds(creds)

	s := grpc.NewServer(opts)

	fmt.Println("Server GRPC has been binding: " + bindingGrpcPort)

	// grpc đã viết sẵn chỉ new lên thôi
	//s := grpc.NewServer()

	calculatorpb.RegisterCalculatorServiceServer(s, &server{})
	reflection.Register(s)
	fmt.Println("calculator is running ..")
	err = s.Serve(lis)
	if err != nil {
		log.Fatalf("error while create listen %v", err)
	}
}