【Go】gRPC通信_サンプル実装(win)

メモとしてgRPC通信のサンプル実装を残す。

<h1>【環境について】</h1>

・go version:go1.19.2
・protoc version:libprotoc 22.0
・protoc-gen-go version:v1.28.0
・protoc-gen-go-grpc version:1.2.0

<h1>フォルダ構成</h1>

```
   grpc
    ├─go.mod
    ├─go.sum
    └─examples
          │        
          ├─greeter_client
          │        └ main.go     
          ├─greeter_server
          │        └ main.go      
          └─helloworld
                   ├ helloworld.pb.go
                   ├ helloworld.proto
                   └ helloworld_grpc.pb.go
```


<h1>【protocを設定】</h1>

■protocをインストール
①<a href="https://github.com/protocolbuffers/protobuf/releases">こちら</a>から「protoc-xxx-win32.zip」を取得。

■環境変数の設定
①コントロールパネル>システムとセキュリティ>システムを開く
②システム詳細設定をクリックしてシステムプロパティを開く
③環境変数をクリック
④「新規」をクリックして変数名と値(protocを保存しておきたいパス)を設定。
⑤変数:Pathにカーソルを合わせて「編集」をクリック。
⑥環境変数名の編集画面で「新規」をクリックして値(protocを保存しておきたいパス)を入力
⑦コマンドプロンプト等で「protoc --version」を入力して下記のように表示される事を確認

```
protoc --version 
libprotoc 22.0
```

<h1>【gRPCをインストール】</h1>
※前提:go modファイルを作成してから実施して下さい。

```
$ go get -u google.golang.org/grpc
```

<h1>protoc-gen-go,protoc-gen-go-grpcをインストール</h1>

```
 go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.28
$ go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.2
```

<h1>protoファイルの作成</h1>

```
syntax = "proto3";

// option java_multiple_files = true;
// option java_package = "io.grpc.examples.helloworld";
// option java_outer_classname = "HelloWorldProto";
// option go_package = "proto/;proto";

option go_package = "google.golang.org/grpc/examples/helloworld/helloworld";
option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";

package proto;

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}
```

作成後下記コマンドを実行

```
protoc --go_out=. --go-grpc_out=./helloworld ./helloworld/*.proto
```

「helloworld.pb.go」と「helloworld_grpc.pb.go」が作成出来ている事を確認。

helloworld.pb.go
```
// Code generated by protoc-gen-go. DO NOT EDIT.
// versions:
// 	protoc-gen-go v1.28.0
// 	protoc        v4.22.0
// source: helloworld/helloworld.proto

package helloworld

import (
	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
	reflect "reflect"
	sync "sync"
)

const (
	// Verify that this generated code is sufficiently up-to-date.
	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
	// Verify that runtime/protoimpl is sufficiently up-to-date.
	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
)

// The request message containing the user's name.
type HelloRequest struct {
	state         protoimpl.MessageState
	sizeCache     protoimpl.SizeCache
	unknownFields protoimpl.UnknownFields

	Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
}

func (x *HelloRequest) Reset() {
	*x = HelloRequest{}
	if protoimpl.UnsafeEnabled {
		mi := &file_helloworld_helloworld_proto_msgTypes[0]
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		ms.StoreMessageInfo(mi)
	}
}

func (x *HelloRequest) String() string {
	return protoimpl.X.MessageStringOf(x)
}

func (*HelloRequest) ProtoMessage() {}

func (x *HelloRequest) ProtoReflect() protoreflect.Message {
	mi := &file_helloworld_helloworld_proto_msgTypes[0]
	if protoimpl.UnsafeEnabled && x != nil {
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		if ms.LoadMessageInfo() == nil {
			ms.StoreMessageInfo(mi)
		}
		return ms
	}
	return mi.MessageOf(x)
}

// Deprecated: Use HelloRequest.ProtoReflect.Descriptor instead.
func (*HelloRequest) Descriptor() ([]byte, []int) {
	return file_helloworld_helloworld_proto_rawDescGZIP(), []int{0}
}

func (x *HelloRequest) GetName() string {
	if x != nil {
		return x.Name
	}
	return ""
}

// The response message containing the greetings
type HelloReply struct {
	state         protoimpl.MessageState
	sizeCache     protoimpl.SizeCache
	unknownFields protoimpl.UnknownFields

	Message string `protobuf:"bytes,1,opt,name=message,proto3" json:"message,omitempty"`
}

func (x *HelloReply) Reset() {
	*x = HelloReply{}
	if protoimpl.UnsafeEnabled {
		mi := &file_helloworld_helloworld_proto_msgTypes[1]
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		ms.StoreMessageInfo(mi)
	}
}

func (x *HelloReply) String() string {
	return protoimpl.X.MessageStringOf(x)
}

func (*HelloReply) ProtoMessage() {}

func (x *HelloReply) ProtoReflect() protoreflect.Message {
	mi := &file_helloworld_helloworld_proto_msgTypes[1]
	if protoimpl.UnsafeEnabled && x != nil {
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		if ms.LoadMessageInfo() == nil {
			ms.StoreMessageInfo(mi)
		}
		return ms
	}
	return mi.MessageOf(x)
}

// Deprecated: Use HelloReply.ProtoReflect.Descriptor instead.
func (*HelloReply) Descriptor() ([]byte, []int) {
	return file_helloworld_helloworld_proto_rawDescGZIP(), []int{1}
}

func (x *HelloReply) GetMessage() string {
	if x != nil {
		return x.Message
	}
	return ""
}

var File_helloworld_helloworld_proto protoreflect.FileDescriptor

var file_helloworld_helloworld_proto_rawDesc = []byte{
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	0x6f, 0x33,
}

var (
	file_helloworld_helloworld_proto_rawDescOnce sync.Once
	file_helloworld_helloworld_proto_rawDescData = file_helloworld_helloworld_proto_rawDesc
)

func file_helloworld_helloworld_proto_rawDescGZIP() []byte {
	file_helloworld_helloworld_proto_rawDescOnce.Do(func() {
		file_helloworld_helloworld_proto_rawDescData = protoimpl.X.CompressGZIP(file_helloworld_helloworld_proto_rawDescData)
	})
	return file_helloworld_helloworld_proto_rawDescData
}

var file_helloworld_helloworld_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
var file_helloworld_helloworld_proto_goTypes = []interface{}{
	(*HelloRequest)(nil), // 0: proto.HelloRequest
	(*HelloReply)(nil),   // 1: proto.HelloReply
}
var file_helloworld_helloworld_proto_depIdxs = []int32{
	0, // 0: proto.Greeter.SayHello:input_type -> proto.HelloRequest
	1, // 1: proto.Greeter.SayHello:output_type -> proto.HelloReply
	1, // [1:2] is the sub-list for method output_type
	0, // [0:1] is the sub-list for method input_type
	0, // [0:0] is the sub-list for extension type_name
	0, // [0:0] is the sub-list for extension extendee
	0, // [0:0] is the sub-list for field type_name
}

func init() { file_helloworld_helloworld_proto_init() }
func file_helloworld_helloworld_proto_init() {
	if File_helloworld_helloworld_proto != nil {
		return
	}
	if !protoimpl.UnsafeEnabled {
		file_helloworld_helloworld_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
			switch v := v.(*HelloRequest); i {
			case 0:
				return &v.state
			case 1:
				return &v.sizeCache
			case 2:
				return &v.unknownFields
			default:
				return nil
			}
		}
		file_helloworld_helloworld_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
			switch v := v.(*HelloReply); i {
			case 0:
				return &v.state
			case 1:
				return &v.sizeCache
			case 2:
				return &v.unknownFields
			default:
				return nil
			}
		}
	}
	type x struct{}
	out := protoimpl.TypeBuilder{
		File: protoimpl.DescBuilder{
			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
			RawDescriptor: file_helloworld_helloworld_proto_rawDesc,
			NumEnums:      0,
			NumMessages:   2,
			NumExtensions: 0,
			NumServices:   1,
		},
		GoTypes:           file_helloworld_helloworld_proto_goTypes,
		DependencyIndexes: file_helloworld_helloworld_proto_depIdxs,
		MessageInfos:      file_helloworld_helloworld_proto_msgTypes,
	}.Build()
	File_helloworld_helloworld_proto = out.File
	file_helloworld_helloworld_proto_rawDesc = nil
	file_helloworld_helloworld_proto_goTypes = nil
	file_helloworld_helloworld_proto_depIdxs = nil
}

```

helloworld_grpc.pb.go

```
// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
// versions:
// - protoc-gen-go-grpc v1.2.0
// - protoc             v4.22.0
// source: helloworld/helloworld.proto

package helloworld

import (
	context "context"
	grpc "google.golang.org/grpc"
	codes "google.golang.org/grpc/codes"
	status "google.golang.org/grpc/status"
)

// This is a compile-time assertion to ensure that this generated file
// is compatible with the grpc package it is being compiled against.
// Requires gRPC-Go v1.32.0 or later.
const _ = grpc.SupportPackageIsVersion7

// GreeterClient is the client API for Greeter service.
//
// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
type GreeterClient interface {
	// Sends a greeting
	SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error)
}

type greeterClient struct {
	cc grpc.ClientConnInterface
}

func NewGreeterClient(cc grpc.ClientConnInterface) GreeterClient {
	return &greeterClient{cc}
}

func (c *greeterClient) SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error) {
	out := new(HelloReply)
	err := c.cc.Invoke(ctx, "/proto.Greeter/SayHello", in, out, opts...)
	if err != nil {
		return nil, err
	}
	return out, nil
}

// GreeterServer is the server API for Greeter service.
// All implementations must embed UnimplementedGreeterServer
// for forward compatibility
type GreeterServer interface {
	// Sends a greeting
	SayHello(context.Context, *HelloRequest) (*HelloReply, error)
	mustEmbedUnimplementedGreeterServer()
}

// UnimplementedGreeterServer must be embedded to have forward compatible implementations.
type UnimplementedGreeterServer struct {
}

func (UnimplementedGreeterServer) SayHello(context.Context, *HelloRequest) (*HelloReply, error) {
	return nil, status.Errorf(codes.Unimplemented, "method SayHello not implemented")
}
func (UnimplementedGreeterServer) mustEmbedUnimplementedGreeterServer() {}

// UnsafeGreeterServer may be embedded to opt out of forward compatibility for this service.
// Use of this interface is not recommended, as added methods to GreeterServer will
// result in compilation errors.
type UnsafeGreeterServer interface {
	mustEmbedUnimplementedGreeterServer()
}

func RegisterGreeterServer(s grpc.ServiceRegistrar, srv GreeterServer) {
	s.RegisterService(&Greeter_ServiceDesc, srv)
}

func _Greeter_SayHello_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
	in := new(HelloRequest)
	if err := dec(in); err != nil {
		return nil, err
	}
	if interceptor == nil {
		return srv.(GreeterServer).SayHello(ctx, in)
	}
	info := &grpc.UnaryServerInfo{
		Server:     srv,
		FullMethod: "/proto.Greeter/SayHello",
	}
	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
		return srv.(GreeterServer).SayHello(ctx, req.(*HelloRequest))
	}
	return interceptor(ctx, in, info, handler)
}

// Greeter_ServiceDesc is the grpc.ServiceDesc for Greeter service.
// It's only intended for direct use with grpc.RegisterService,
// and not to be introspected or modified (even as a copy)
var Greeter_ServiceDesc = grpc.ServiceDesc{
	ServiceName: "proto.Greeter",
	HandlerType: (*GreeterServer)(nil),
	Methods: []grpc.MethodDesc{
		{
			MethodName: "SayHello",
			Handler:    _Greeter_SayHello_Handler,
		},
	},
	Streams:  []grpc.StreamDesc{},
	Metadata: "helloworld/helloworld.proto",
}

```

<h1>【server側の実装】</h1>

```
//go:generate protoc -I ../helloworld --go_out=plugins=grpc:../helloworld ../helloworld/helloworld.proto

// Package main implements a server for Greeter service.
package main

import (
	"context"
	"log"
	"net"

	"google.golang.org/grpc"
	pb "google.golang.org/grpc/examples/helloworld/helloworld"
)

const (
    port = ":50051"
)

type server struct{
    pb.UnimplementedGreeterServer
}

// SayHelloメソッドを実装
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    log.Printf("Received: %v", in.Name)
    return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

func main() {
   // リッスン処理
    lis, err := net.Listen("tcp", port)
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }

    // サーバ起動
    s := grpc.NewServer()
    pb.RegisterGreeterServer(s, &server{})
    if err := s.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }
}
```

<h1>【Client側の実装】</h1>

```
// Package main implements a client for Greeter service.
package main

import (
	"context"
	"log"
	"os"
	"time"

	"google.golang.org/grpc"
	pb "google.golang.org/grpc/examples/helloworld/helloworld"
)

const (
    address     = "localhost:50051"
    defaultName = "world"
)

func main() {
    // gRPCコネクションの作成
    conn, err := grpc.Dial(address, grpc.WithInsecure())
    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }
    defer conn.Close()
    c := pb.NewGreeterClient(conn)

    // 引数の準備
    name := defaultName
    if len(os.Args) > 1 {
        name = os.Args[1]
    }

        // contextの準備
    ctx, cancel := context.WithTimeout(context.Background(), time.Second)
    defer cancel()

        // SayHelloメソッドの呼び出し
    r, err := c.SayHello(ctx, &pb.HelloRequest{Name: name})
    if err != nil {
        log.Fatalf("could not greet: %v", err)
    }
    log.Printf("Greeting: %s", r.Message)
}
```

<h1>動作確認</h1>

サーバーを動かす
```
go run greeter_server/main.go
```

リクエストを実行
```
go run main.go
2023/02/20 00:19:51 Greeting: Hello world
```