通过grpc-gateway对外提供基于grpc的http接口API

grpc优点不再多叙述，但如何对外提供Restful接口的，而有不希望重复开发相同的功能可以使用grpc-gateway将grpc转换为对外的Restful API。

安装

go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway
go get -u github.com/micro/protobuf/{proto,protoc-gen-go}

如果只是使用，其实处理起来很简单在原有grpc的.proto文件中添加相应的import文件和http配置声明即可。

import文件

import “google/api/annotations.proto”;

http配置声明

service Bookinfo {
    // get book information
    rpc Getall (GetallRequest) returns (GetallResponse) {
        option (google.api.http) = {
            post: "/bookinfo/getall"
            body: "*"
        };
    };
}

大概说明

bookinfo.proto文件

syntax = "proto3";

package bookinfo;

import "google/api/annotations.proto";

option go_package = "bookinfopb";

// The book service makes it possible to get or set book's detail information
service Bookinfo {
    // get book information
    rpc Getall (GetallRequest) returns (GetallResponse) {
        option (google.api.http) = {
            post: "/bookinfo/getall"
            body: "*"
        };
    };
    // add books information
    rpc Add (AddRequest) returns (AddResponse){
        option (google.api.http) = {
            post: "/bookinfo/add"
            body: "*"
        };
    };
}

message GetallRequest {
    // ID of user
    string userid = 1;
}

message GetallResponse {
    // Book info list
    repeated BookInfo bookinfolist = 1;
}

message BookInfo {
    // Name of book
    string book_name = 1;
    // Author
    string author = 2;
    // Chapters name
    repeated ChapterInfo chapters_info = 3;
}

message ChapterInfo {
    // Chapter number
    sint32 chapter_num = 1;
    // Chapter name
    string chapter_name = 2;
    // Words cound
    sint32 words_count = 3;
}

message AddRequest {
    // Books information
    repeated BookInfo books_info = 1;
}

message AddResponse {
    repeated sint32 field = 1;
}

定义请求接口名，参数和返回结果

Getall接口的参数是string类型的userid。返回结果是书籍详情（BookInfo）的数组(通过repeated标识)

生成grpc服务的stub文件

protoc -I/usr/local/include -I. \
    -I$(GOPATH)/src \
    -I$(GOPATH)/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
    --go_out=plugins=grpc:. bookinfo-srv/proto/bookinfo/bookinfo.proto

生成bookinfo.pb.go文件

生成grpc-gateway的stub文件

protoc -I/usr/local/include -I. \

-I $(GOPATH)/src \

-I $(GOPATH)/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \

–grpc-gateway_out=logtostderr=true:. bookinfo-srv/proto/bookinfo/bookinfo.proto

生成bookinfo.pb.gw.go文件

grpc功能的实现

• service.go

  package main

  import (

  pb "grpcT1/bookinfo-srv/proto/bookinfo"
     bkinfoprocess "grpcT1/bookinfo-srv/process"
     "net"
     "log"
     "google.golang.org/grpc"

  )

  const (

  PORT = ":50051"

  )

  func main() {

  listener, err := net.Listen("tcp", PORT)
     if err != nil {
         log.Fatalf("failed to listen: %v", err)
     }
     log.Printf("listen on: %s\n", PORT)
  
     server := grpc.NewServer()
  
  
     pb.RegisterBookinfoServer(server, bkinfoprocess.NewBookinfo())
  
     if err := server.Serve(listener); err != nil {
         log.Fatalf("failed to serve: %v", err)
     }

  }

其中RegisterBookinfoServer方法是在bookinfo.pb.go中定义和实现的

• process/bookinfo.go定义的接口方法的具体逻辑实现

  package bookinfoprocess

  import (

  bookinfo "grpcT1/bookinfo-srv/proto/bookinfo"
     "context"
     "fmt"

  )

  type bookinfosrvc struct {}

  func NewBookinfo() bookinfo.BookinfoServer {

  return &bookinfosrvc{}

  }

  func (s bookinfosrvc) Getall(ctx context.Context, p bookinfo.GetallRequest) (*bookinfo.GetallResponse, error) {

  res := &bookinfo.GetallResponse{}
     fmt.Println("bookinfo.getall")
     cpsInfo := make([]*bookinfo.ChapterInfo,4)
     cpsInfo[0] = &bookinfo.ChapterInfo{ChapterNum:1, ChapterName:"序言", WordsCount:3259}
     cpsInfo[1] = &bookinfo.ChapterInfo{ChapterNum:2, ChapterName:"布尔", WordsCount:4559}
     cpsInfo[2] = &bookinfo.ChapterInfo{ChapterNum:3, ChapterName:"字符", WordsCount:7559}
     cpsInfo[3] = &bookinfo.ChapterInfo{ChapterNum:4, ChapterName:"函数", WordsCount:7859}
  
     bkInfo := &bookinfo.BookInfo{BookName:"Ugly language", Author:"Bill", 
                         ChaptersInfo:cpsInfo}
  
     res.Bookinfolist = append(res.Bookinfolist, bkInfo)
  
     return res, nil

  }

  func (s bookinfosrvc) Add(ctx context.Context, p bookinfo.AddRequest) (*bookinfo.AddResponse, error) {

  return nil, nil

  }

gateway方式对外提供http接口

• gateway/main.go

  package main

  import (

  "flag"
   "net/http"
    
   "github.com/golang/glog"
   "golang.org/x/net/context"
   "github.com/grpc-ecosystem/grpc-gateway/runtime"
   "google.golang.org/grpc"
        
   gw "grpcT1/bookinfo-srv/proto/bookinfo"

  )

  var (

  echoEndpoint = flag.String("getall_endpoint", "rpcserver:50051", "endpoint of BookInfoService")

  )

  func run() error {

  ctx := context.Background()
   ctx, cancel := context.WithCancel(ctx)
   defer cancel()
    
   mux := runtime.NewServeMux()
   opts := []grpc.DialOption{grpc.WithInsecure()}
   err := gw.RegisterBookinfoHandlerFromEndpoint(ctx, mux, *echoEndpoint, opts)
   if err != nil {
     return err
   }
    
   return http.ListenAndServe(":8080", mux)

  }

  func main() {

  flag.Parse()
   defer glog.Flush()
    
   if err := run(); err != nil {
     glog.Fatal(err)
   }

  }

其中RegisterBookinfoHandlerFromEndpoint方法在bookinfo.pb.gw.go中定义和实现

grpc请求

• client/main.go

  package main

  import (

  pb "grpcT1/bookinfo-srv/proto/bookinfo"
     "google.golang.org/grpc"
     "log"
     "context"

  )

  const (

  ADDRESS = "rpcserver:50051"

  )

  func main() {

  // 连接到 gRPC 服务器
     conn, err := grpc.Dial(ADDRESS, grpc.WithInsecure())
     if err != nil {
         log.Fatalf("connect error: %v", err)
     }
     defer conn.Close()
  
     // 初始化 gRPC 客户端
     client := pb.NewBookinfoClient(conn)
  
     resp, err := client.Getall(context.Background(), &pb.GetallRequest{Userid:"tt"})
     if err != nil {
         log.Fatalf("Getall error: %v", err)
     }
  
     length := len(resp.Bookinfolist)
     for i:=0;i
  }
  

client调用grpc接口的实现。NewBookinfoClient方法在bookinfo.pb.go中定义和实现

http请求测试

curl -X POST -k http://localhost:8080/bookinfo/getall -d '{"userid":"tt"}'

详细代码可以从这取得 https://github.com/BinWang-sh...

根目录下有makefile可生成stub和docker镜像

Docker目录下有docker-compose文件执行docker-compose up可以直接run