You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: server.go
    path of file: ./repos/pixie/src/stirling/testing/demo_apps/go_grpc_tls_pl/server
    
    the code of the file until where you have to start completion: /*
 * Copyright 2018- The Pixie Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

package main

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"net"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	log "github.com/sirupsen/logrus"
	"github.com/spf13/pflag"
	"github.com/spf13/viper"
	"golang.org/x/net/http2"
	"golang.org/x/net/http2/h2c"
	"google.golang.org/grpc"

	"px.dev/pixie/src/stirling/testing/demo_apps/go_grpc_tls_pl/server/greetpb"
)

const (
	port = ":50400"
)

// Server is used to implement the Greeter.
type Server struct{}

// SayHello responds to a the basic HelloRequest.
func (s *Server) SayHello(ctx context.Context, in *greetpb.HelloRequest) (*greetpb.HelloReply, error) {
	return &greetpb.HelloReply{Message: "Hello " +
    
func main() {
	pflag.String("server_tls_cert", "", "Path to server.crt")
	pflag.String("server_tls_key", "", "Path to server.key")
	pflag.String("tls_ca_cert", "", "Path to ca.crt")
	pflag.Parse()
	viper.BindPFlags(pflag.CommandLine)

	pair, err := tls.LoadX509KeyPair(viper.GetString("server_tls_cert"), viper.GetString("server_tls_key"))
	if err != nil {
		log.WithError(err).Fatal("failed to load keys")
	}

	certPool := x509.NewCertPool()
	ca, err := os.ReadFile(viper.GetString("tls_ca_cert"))
	if err != nil {
		log.WithError(err).Fatal("failed to read CA cert")
	}

	if ok := certPool.AppendCertsFromPEM(ca); !ok {
		log.Fatal("failed to append CA cert")
	}

	config := &tls.Config{
		Certificates: []tls.Certificate{pair},
		NextProtos:   []string{"h2"},
		ClientCAs:    certPool,
	}

	lis, err := net.Listen("tcp", port)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}

	grpcServer := grpc.NewServer()
	greetpb.RegisterGreeterServer(grpcServer, &Server{})

	muxHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		grpcServer.ServeHTTP(w, r)
	})

	httpServer := &http.Server{
		Addr:           port,
		Handler:        h2c.NewHandler(muxHandler, &http2.Server{}),
		TLSConfig:      config,
		ReadTimeout:    1800 * time.Second,
		WriteTimeout:   1800 * time.Second,
		MaxHeaderBytes: 1 << 20,
	}

	lis = tls.NewListener(lis, httpServer.TLSConfig)
	go httpServer.Serve(lis) //nolint:errcheck // This returns an error on graceful shutdown too.

	// The test relies on the following to check for server readiness
	log.Print("Starting HTTP/2 server")

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

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	err = httpServer.Shutdown(ctx)
	if err != nil {
		log.WithError(err).Error("http2 server Shutdown() failed")
	}
}