gRPC service with HTTP interface?

While Go-Zero brought developers an excellent RESTful and gRPC service development experience, more expectations were raised. to like:

• i want to write the code only once
• I want both gRPC and HTTP interfaces

It makes sense! You see what users say.

User A: A set of arguments, HTTP and gRPC together.

User B: If Go-Zero can simplify this step, I think it will become the best microservices framework ever.

So I got into a deep thought: the user is never wrong, but do we want to take that for granted?

Here comes the article.

We are very familiar with this service. Create a new directory, call it grpc-restufland put one sum.proto file in

syntax = "proto3";package sum;
option go_package="./pb";message SumRequest {
int64 a = 1;
int64 b = 2;
}message SumResponse {
int64 result = 1;
}service Sum {
rpc Add(SumRequest) returns (SumResponse) {}
}

One-click generation, you know.

$ goctl rpc protoc --go_out=. --go-grpc_out=. --zrpc_out=. sum.proto

see what you get

.
├── etc
│ └── sum.yaml
├── go.mod
├── internal
│ ├── config
│ │ └── config.go
│ ├── logic
│ │ └── addlogic.go
│ ├── server
│ │ └── sumserver.go
│ └── svc
│ └── servicecontext.go
├─ pb
│ ├── sum.pb.go
│ └── sum_grpc.pb.go
├─ sum
│ └── sum.go
├── sum.go
└── sum.proto

To implement business logic, modify Add method in internal/logic/addlogic.go as follows.

func (l *AddLogic) Add(in *pb.SumRequest) (*pb.SumResponse, error) {
return &pb.SumResponse{
Result: in.A+in.B,
}, nil
}

You can run it, and the business logic is present (though it’s too simple for demo purpose.)

$ go mod tidy && go run sum.go
Starting rpc server at 127.0.0.1:8080...

For those who are familiar with Go-Zero, there is no highlight (new knowledge) here, let’s move on~

First, let’s update to Go-Zero v1.4.0 Edition,

$ go get -u github.com/zeromicro/go-zero@latest

Revised sum.protoi made a new one sum-api.protoas follows

syntax = "proto3";package sum;
option go_package="./pb";import "google/api/annotations.proto";message SumRequest {
int64 a = 1;
int64 b = 2;
}message SumResponse {
int64 result = 1;
}service Sum {
rpc Add(SumRequest) returns (SumResponse) {
option (google.api.http) = {
post: "/v1/sum"
body: "*"
};
}
}

protoc --include_imports --proto_path=. --descriptor_set_out=sum.pb sum-api.proto

Revised internal/config/config.go Looks like this (partially)

type Config struct {
zrpc.RpcServerConf
Gateway gateway.GatewayConf
Gateway.GatewayConf }

Revised etc/sum.yaml Is in this type

Gateway:
Name: gateway
Port: 8081
Upstreams:
- Grpc:
Endpoints:
- localhost:8080
ProtoSets:
- sum.pb

to create gateway and use ServiceGroup to manage gRPC server And gateway serverThe code part is as follows.

gw := gateway.MustNewServer(c.Gateway)
group := service.NewServiceGroup()
group.Add(s)
group.Add(gw)
defer group.Stop()    fmt.Printf("Starting rpc server at %s... \n", c.ListenOn)
fmt.Printf("Starting gateway at %s:%d... \n", c.Gateway.Host, c.Gateway.Port)
group.Start()

let’s start the service

$ go run sum.go
Starting rpc server at 127.0.0.1:8080...
Starting gateway at 0.0.0.0:8081...

test it with curl

$ curl -i -H "Content-Type: application/json" -d '{"a":2, "b":3}' localhost:8081/v1/sum
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Traceparent: 00-ad5b7df7a834a1c05ee64999e3310811-195ba1f4f9956cc4-00
Date: Mon, 18 Jul 2022 14:33:11 GMT
Content-Length: 20{
"result": "5"
}

and see the link information in our gateway And gRPC Log that corresponds to what the client receives is awesome!

{"@timestamp": "2022-07-18T22:33:11.437+08:00", "caller": "serverinterceptors/statinterceptor.go:76", "content": "127.0.0.1:61635 - /sum. Sum/Add - {\"a\":2,\"b\":3}", "duration": "0.0ms", "level": "info", "span": "b3c85cd32a76f8c9", "trace":" ad5b7df7a834a1c05ee64999e3310811"}
{"@timestamp": "2022-07-18T22:33:11.438+08:00", "caller": "handler/loghandler.go:197", "content":"[HTTP] 200 - POST /v1/sum - 127.0.0.1: 61662 - curl/7.79.1", "duration": "0.7ms", "level": "info", "span": "195ba1f4f9956cc4", "trace": "ad5b7df7a834a1c05ee64999e3310811"}

You see, adding HTTP interface for us gRPC Is the service too easy? Isn’t it?

Also, don’t underestimate this simple gatewayConfiguration will automatically load balance if it is docked gRPC There’s service behind it, and you can even customize the middleware to control what you want.

By the way, here is the complete code for this example.

https://github.com/kevwan/grpc-restful

https://github.com/zeromicro/go-zero

feel free to use go-zero And Star to support us!