gRPC: 如何让 gRPC 提供 Restful API 服务?
介绍
本文将介绍如何让一个 gRPC 服务,同时提供 gRPC 和 Restful API。
- 为了能让 gRPC 提供 REST API,我们需要使用 grpc-gateway
请访问如下地址获取完整教程:https://rkdev.info/cn
https://rkdocs.netlify.app/cn (备用)
使用 rk-boot
rk-boot 是集成了 Gin, gRPC 和一系列流行 Go 语言框架的启动器,用户可以通过 rk-boot 快速启动企业级 Go 语言微服务。
先决条件
使用过 GRPC 的用户都应该知道,protocol buffer 文件需要使用相关的命令行,把 .proto 文件编译成 .go 文件。
根据不同需要,会使用到不同的命令行文件。以 Go 语言为例,我们需要大致如下几个命令行文件。
工具 |
介绍 |
安装 |
---|---|---|
protocol buffer 编译所需的命令行 |
||
从 proto 文件,生成 .go 文件 |
||
从 proto 文件,生成 GRPC 相关的 .go 文件 |
||
从 proto 文件,生成 grpc-gateway 相关的 .go 文件 |
||
从 proto 文件,生成 swagger 界面所需的参数文件 |
除了安装上述命令行,我们还需要根据需要,运行至少4种不同命令来编译 *.proto 文件,非常晦涩难懂。
具体操作方式可参考我的前一篇文章:【GRPC: 使用 Buf 快速编译 GRPC proto 文件】
或者访问:【https://rkdev.info/cn/docs/bootstrapper/user-guide/grpc-golang/basic/grpc-gateway/】
安装
- go get github.com/rookie-ninja/rk-boot
- go get github.com/rookie-ninja/rk-grpc
快速开始
1.创建 api/v1/greeter.proto
- syntax = "proto3";
-
- package api.v1;
-
- option go_package = "api/v1/greeter";
-
- service Greeter {
- rpc Greeter (GreeterRequest) returns (GreeterResponse) {}
- }
-
- message GreeterRequest {
- string name = 1;
- }
-
- message GreeterResponse {
- string message = 1;
- }
2.创建 api/v1/gw_mapping.yaml
- type: google.api.Service
- config_version: 3
-
- # Please refer google.api.Http in https://github.com/googleapis/googleapis/blob/master/google/api/http.proto file for details.
- http:
- rules:
- - selector: api.v1.Greeter.Greeter
- get: /api/v1/greeter
3.创建 buf.yaml
- version: v1beta1
- name: github.com/rk-dev/rk-demo
- build:
- roots:
- - api
4.创建 buf.gen.yaml
- version: v1beta1
- plugins:
- # protoc-gen-go needs to be installed, generate go files based on proto files
- - name: go
- out: api/gen
- opt:
- - paths=source_relative
- # protoc-gen-go-grpc needs to be installed, generate grpc go files based on proto files
- - name: go-grpc
- out: api/gen
- opt:
- - paths=source_relative
- - require_unimplemented_servers=false
- # protoc-gen-grpc-gateway needs to be installed, generate grpc-gateway go files based on proto files
- - name: grpc-gateway
- out: api/gen
- opt:
- - paths=source_relative
- - grpc_api_configuration=api/v1/gw_mapping.yaml
- # protoc-gen-openapiv2 needs to be installed, generate swagger config files based on proto files
- - name: openapiv2
- out: api/gen
- opt:
- - grpc_api_configuration=api/v1/gw_mapping.yaml
5.编译 proto file
- $ buf generate
如下的文件会被创建。
- $ tree api/gen
- api/gen
- └── v1
- ├── greeter.pb.go
- ├── greeter.pb.gw.go
- ├── greeter.swagger.json
- └── greeter_grpc.pb.go
-
- 1 directory, 4 files
6.创建 boot.yaml
- grpc:
- - name: greeter # Name of grpc entry
- port: 8080 # Port of grpc entry
- enabled: true # Enable grpc entry
- enableReflection: true
7. 创建 main.go
- package main
-
- import (
- "context"
- "fmt"
- "github.com/rookie-ninja/rk-boot"
- "github.com/rookie-ninja/rk-demo/api/gen/v1"
- "github.com/rookie-ninja/rk-grpc/boot"
- "google.golang.org/grpc"
- )
-
- // Application entrance.
- func main() {
- // Create a new boot instance.
- boot := rkboot.NewBoot()
-
- // ***************************************
- // ******* Register GRPC & Gateway *******
- // ***************************************
-
- // Get grpc entry with name
- grpcEntry := boot.GetEntry("greeter").(*rkgrpc.GrpcEntry)
- // Register grpc registration function
- grpcEntry.AddRegFuncGrpc(registerGreeter)
- // Register grpc-gateway registration function
- grpcEntry.AddRegFuncGw(greeter.RegisterGreeterHandlerFromEndpoint)
-
- // Bootstrap
- boot.Bootstrap(context.Background())
-
- // Wait for shutdown sig
- boot.WaitForShutdownSig(context.Background())
- }
-
- // Implementation of [type GrpcRegFunc func(server *grpc.Server)]
- func registerGreeter(server *grpc.Server) {
- greeter.RegisterGreeterServer(server, &GreeterServer{})
- }
-
- // Implementation of grpc service defined in proto file
- type GreeterServer struct{}
-
- func (server *GreeterServer) Greeter(ctx context.Context, request *greeter.GreeterRequest) (*greeter.GreeterResponse, error) {
- return &greeter.GreeterResponse{
- Message: fmt.Sprintf("Hello %s!", request.Name),
- }, nil
- }
8.文件夹结构
- $ tree
- .
- ├── api
- │ ├── gen
- │ │ └── v1
- │ │ ├── greeter.pb.go
- │ │ ├── greeter.pb.gw.go
- │ │ ├── greeter.swagger.json
- │ │ └── greeter_grpc.pb.go
- │ └── v1
- │ ├── greeter.proto
- │ └── gw_mapping.yaml
- ├── boot.yaml
- ├── buf.gen.yaml
- ├── buf.yaml
- ├── go.mod
- ├── go.sum
- └── main.go
-
- 4 directories, 12 files
9.验证
rk-boot 会使用同一个端口来映射 gRPC 和 gRPC-gateway,非常方便。
- $ go run main.go
- 验证 Restful API
- $ curl "localhost:8080/api/v1/greeter?name=rk-dev"
- {"message":"Hello rk-dev!"}
- 验证 gRPC$ grpcurl -d '{"name": "rk-dev"}' -plaintext localhost:8080 api.v1.Greeter.Greeter
{
"message": "Hello rk-dev!"
}
Gateway server option
rk-boot 有一个 enableRkGwOption 选项,启动之后,会包含如下几个功能。
RK 推荐的 server option,提供如下的功能。
功能 |
详情 |
---|---|
HttpErrorHandler |
主要代码从原有 grpc-gateway 代码中抄写而来,启动器会返回 RK 推荐的 API 错误结构 |
MarshalerOption |
protojson.MarshalOptions{UseProtoNames: false, EmitUnpopulated: true},UnmarshalOptions: protojson.UnmarshalOptions{}} |
Metadata |
注入如下 GRPC metadata: x-forwarded-method, x-forwarded-path, x-forwarded-scheme, x-forwarded-user-agent 和 x-forwarded-remote-addr |
OutgoingHeaderMatcher |
把原有的 grpc metadata 转发到 http 头部(没有前缀) |
IncomingHeaderMatcher |
把原有的 http 头部 转发到 grpc metadata(没有前缀) |
1.启动 enableRkGwOption
为了能够验证,我们会添加 gRPC 日志拦截器。
- boot.yaml
- grpc:
- - name: greeter # Name of grpc entry
- port: 8080 # Port of grpc entry
- enabled: true # Enable grpc entry
- enableReflection: true # Enable grpc reflection
- enableRkGwOption: true # Enable rk style grpc gateway server option
- interceptors:
- loggingZap:
- enabled: true # Enable logging interceptor for validation
2.验证日志
- $ curl "localhost:8080/api/v1/greeter?name=rk-dev"
gwMethod, gwPath, gwScheme, gwUserAgent 将会记录到日志中
- ------------------------------------------------------------------------
- endTime=2021-07-09T21:03:43.518106+08:00
- ...
- payloads={"grpcMethod":"Greeter","grpcService":"api.v1.Greeter","grpcType":"unaryServer","gwMethod":"GET","gwPath":"/v1/greeter","gwScheme":"http","gwUserAgent":"curl/7.64.1"}
- ...
3.验证传入的 metadata
- func (server *GreeterServer) Greeter(ctx context.Context, request *greeter.GreeterRequest) (*greeter.GreeterResponse, error) {
- // Print incoming headers
- fmt.Println(rkgrpcctx.GetIncomingHeaders(ctx))
-
- return &greeter.GreeterResponse{
- Message: fmt.Sprintf("Hello %s!", request.Name),
- }, nil
- }
- map[:authority:[0.0.0.0:8080] accept:[*/*] content-type:[application/grpc] user-agent:[grpc-go/1.38.0] x-forwarded-for:[::1] x-forwarded-host:[localhost:8080] x-forwarded-method:[GET] x-forwarded-path:[/v1/greeter] x-forwarded-remote-addr:[[::1]:57082] x-forwarded-scheme:[http] x-forwarded-user-agent:[curl/7.64.1]]
错误映射
grpc-gateway 中,我们需要了解 gateway 到 grpc 的错误映射,即 http 到 grpc 的错误映射。
这是默认的 grpc-gateway 中的错误映射。
GRPC 错误码 |
GRPC 错误码描述 |
Gateway(Http) 错误码 |
Gateway(Http) 错误码描述 |
---|---|---|---|
0 |
OK |
200 |
OK |
1 |
CANCELLED |
408 |
Request Timeout |
2 |
UNKNOWN |
500 |
Internal Server Error |
3 |
INVALID_ARGUMENT |
400 |
Bad Request |
4 |
DEADLINE_EXCEEDED |
504 |
Gateway Timeout |
5 |
NOT_FOUND |
404 |
Not Found |
6 |
ALREADY_EXISTS |
409 |
Conflict |
7 |
PERMISSION_DENIED |
403 |
Forbidden |
8 |
RESOURCE_EXHAUSTED |
429 |
Too Many Requests |
9 |
FAILED_PRECONDITION |
400 |
Bad Request |
10 |
ABORTED |
409 |
Conflict |
11 |
OUT_OF_RANGE |
400 |
Bad Request |
12 |
UNIMPLEMENTED |
501 |
Not Implemented |
13 |
INTERNAL |
500 |
Internal Server Error |
14 |
UNAVAILABLE |
503 |
Service Unavailable |
15 |
DATA_LOSS |
500 |
Internal Server Error |
16 |
UNAUTHENTICATED |
401 |
Unauthorized |
1.验证错误(标准 Go 语言错误)
根据错误映射,将会返回 500。func (server *GreeterServer) Greeter(ctx context.Context, request *greeter.GreeterRequest) (*greeter.GreeterResponse, error) {
return nil, errors.New("error triggered manually")
}
- $ curl "localhost:8080/api/v1/greeter?name=rk-dev"
- {
- "error":{
- "code":500,
- "status":"Internal Server Error",
- "message":"error triggered manually",
- "details":[]
- }
- }
2.验证错误(grpc 错误)
我们需要通过 status.New() 来创建 GRPC 错误。我们推荐使用 rkerror 库中的函数来创建错误。
- func (server *GreeterServer) Greeter(ctx context.Context, request *greeter.GreeterRequest) (*greeter.GreeterResponse, error) {
- return nil, rkerror.PermissionDenied("permission denied manually").Err()
- }
- curl "localhost:8080/v1/greeter?name=rk-dev"
- {
- "error":{
- "code":403,
- "status":"Forbidden",
- "message":"permission denied manually",
- "details":[
- {
- "code":7,
- "status":"PermissionDenied",
- "message":"[from-grpc] permission denied manually"
- }
- ]
- }
- }