Grpc之metadata

hello.proto

syntax="proto3";
package pb;
option go_package = "./pb";
service Greeter {
  rpc SayHello(HelloRequest) returns(HelloReply){}
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

protoc -I . --go_out=. --go-grpc_out=. ./hello.proto

server

package main

import (
	"context"
	"flag"
	"fmt"
	"demo/protos"
	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
	"log"
	"net"
)

var host = "127.0.0.1"

var (
	ServiceName = flag.String("ServiceName", "hello_service", "service name")
	Port        = flag.Int("Port", 50001, "listening port")
)

type server struct {
}

func main() {
	flag.Parse()

	lis, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", *Port))
	if err != nil {
		log.Fatalf("failed to listen:%s", err)
	} else {
		fmt.Printf("listen at :%d\n", *Port)
	}

	defer lis.Close()

	s := grpc.NewServer()
	defer s.GracefulStop()

	protos.RegisterGreeterServer(s, &server{})
	addr := fmt.Sprintf("%s:%d", host, *Port)
	fmt.Printf("server add:%s\n", addr)

	if err := s.Serve(lis); err != nil {
		fmt.Printf("failed to server: %s", err)
	}
}

func (s *server) SayHello(ctx context.Context, in *protos.HelloRequest) (*protos.HelloReply, error) {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		fmt.Printf("get metadata error")
    }else{
        fmt.Println("get metadata success: ",md)
    }
	if t, ok := md["timestamp"]; ok {
		fmt.Printf("timestamp from metadata:\n")
		for i, e := range t {
			fmt.Printf(" %d. %s\n", i, e)
		}
	}
	if t1, ok1 := md["key1"]; ok1 {
		fmt.Printf("key1 from metadata:\n")
		for i, e := range t1 {
			fmt.Printf(" %d . %s\n", i, e)
		}
	}
	if len(md) > 0 {
		for k, v := range md {
			fmt.Printf("%v:%v\n", k, v)
		}
	}
	return &protos.HelloReply{Message: "server: " + in.Name}, nil
}

client

package main

import (
	"context"
	"fmt"
	"demo/protos"
	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
	"time"
)

const (
	timestampFormat = time.StampNano
)

func main() {
	conn, err := grpc.Dial("127.0.0.1:50001", grpc.WithInsecure())
	if err != nil {
		panic(err)
	}

	client := protos.NewGreeterClient(conn)
	md := metadata.Pairs("timestamp", time.Now().Format(timestampFormat))
	md = metadata.New(map[string]string{"key1": "val1", "key2": "val2"})
	ctx := metadata.NewOutgoingContext(context.Background(), md)
	resp, err := client.SayHello(ctx, &protos.HelloRequest{Name: "Hello"})
	if err == nil {
		fmt.Printf("Reply is : %s\n", resp.Message)
	} else {
		fmt.Printf("call server error:%s\n", err)
	}
}

运行

go run server.go
listen at :50001
server add:127.0.0.1:50001
get metadata success:  map[:authority:[127.0.0.1:50001] content-type:[application/grpc] key1:[val1] key2:[val2] user-agent:[grpc-go/1.53.0]]
key1 from metadata:
 0 . val1
:authority:[127.0.0.1:50001]
content-type:[application/grpc]
user-agent:[grpc-go/1.53.0]
key2:[val2]
key1:[val1]
#########################
 go run client.go
Reply is : server: Hello