protoc-gen-httpgo

This is a protoc plugin that generates HTTP server and client code from proto files.

Features

• Generation of both server and client code
  • At the moment works with fasthttp
• Provides multiple options for Marshaling/Unmarshaling:
  • Uses the native encoding/json by default
  • Optional usage of easyjson for performance
  • Optional usage of protojson for better protocol buffer support
• Utilizes google.api.http for defining HTTP paths (also can generate it)
• Supports a wide range of data types in path parameters
• Supports middlewares

Usage

Installation

 go install github.com/MUlt1mate/protoc-gen-httpgo@latest

Definition

Use proto with RPC to define methods

import "google/api/annotations.proto";

service TestService {
  rpc TestMethod (TestMessage) returns (TestMessage) {
    option (google.api.http) = {
      get: "/v1/test/{field1}"
    };
  }
}

message TestMessage {
  string field1 = 1;
  string field2 = 2;
}

Generation

protoc -I=. --httpgo_out=. --httpgo_opt=paths=source_relative example/proto/example.proto

Parameters

Name	Values	Description
paths	source_relative, import	Inherited from protogen, see docs for more details
marshaller	easyjson, protojson	Specifies the data marshaling/unmarshaling package. Uses encoding/json by default.
only	server, client	Use to generate either the server or client code exclusively
autoURI	false, true	Create method URI if annotation is missing.
bodylessMethods	GET;DELETE	List of semicolon separated http methods that should not have a body.

Example of parameters usage:

protoc -I=. --httpgo_out=.  --httpgo_opt=paths=source_relative,marshaller=easyjson,only=server,autoURI=true example/proto/example.proto

The plugin will create an example.httpgo.go file with the following:

• Register{ServiceName}HTTPGoServer - function to register server handlers
• {ServiceName}HTTPGoService - interface with all client methods
• Get{ServiceName}HTTPGoClient - client constructor that implements the above interface

Implementation

Server

package main

import (
	"context"

	"github.com/MUlt1mate/protoc-gen-httpgo/example/implementation"
	"github.com/MUlt1mate/protoc-gen-httpgo/example/proto"
	"github.com/fasthttp/router"
	"github.com/valyala/fasthttp"
)

func serverExample(ctx context.Context) (err error) {
	var (
		handler proto.TestServiceHTTPGoService = &implementation.Handler{}
		r                                      = router.New()
	)
	if err = proto.RegisterTestServiceHTTPGoServer(ctx, r, handler, serverMiddlewares); err != nil {
		return err
	}
	go func() { _ = fasthttp.ListenAndServe(":8080", r.Handler) }()
	return nil
}

Client

package main

import (
	"context"

	"github.com/MUlt1mate/protoc-gen-httpgo/example/proto"
	"github.com/valyala/fasthttp"
)

func clientExample(ctx context.Context) (err error) {
	var (
		client     *proto.TestServiceHTTPGoClient
		httpClient = &fasthttp.Client{}
		host       = "http://localhost:8080"
	)
	if client, err = proto.GetTestServiceHTTPGoClient(ctx, httpClient, host, clientMiddlewares); err != nil {
		return err
	}
	// sending our request
	_, _ = client.TestMethod(context.Background(), &proto.TestMessage{Field1: "value", Field2: "rand"})
	return nil
}

Middlewares

You can define custom middlewares with specific arguments and return values.
Pass a slice of middlewares to the constructor, and they will be invoked in the specified order.
There are middleware examples for logs, timeout, headers, etc.

package implementation

import (
	"log"

	"github.com/valyala/fasthttp"
)

var ServerMiddlewares = []func(ctx *fasthttp.RequestCtx, arg interface{}, next func(ctx *fasthttp.RequestCtx)){
	LoggerServerMiddleware,
}
var ClientMiddlewares = []func(req *fasthttp.Request, handler func(req *fasthttp.Request) (resp *fasthttp.Response, err error)) (resp *fasthttp.Response, err error){
	LoggerClientMiddleware,
}

func LoggerServerMiddleware(
	ctx *fasthttp.RequestCtx, arg interface{},
	next func(ctx *fasthttp.RequestCtx),
) {
	log.Println("server request", arg)
	next(ctx)
	log.Println("server response", string(ctx.Response.Body()))
}

func LoggerClientMiddleware(
	req *fasthttp.Request,
	next func(req *fasthttp.Request) (resp *fasthttp.Response, err error),
) (resp *fasthttp.Response, err error) {
	log.Println("client request", string(req.RequestURI()))
	resp, err = next(req)
	log.Println("client response", string(resp.Body()))
	return resp, err
}

See example for more details.

Conventions

Golang protobuf generator can produce fields with different case:

message InputMsgName {
  int64 value = 1;
}

package main

import "google.golang.org/protobuf/runtime/protoimpl"

type InputMsgName struct {
	state         protoimpl.MessageState
	sizeCache     protoimpl.SizeCache
	unknownFields protoimpl.UnknownFields

	Value int64 `protobuf:"varint,1,opt,name=value,proto3" json:"value,omitempty"`
}

We defined value and got Value. This works just fine, but keep in mind that server will only check for arguments with proto names.

• /v1/test?value=1 - correct
• /v1/test?Value=1 - incorrect

TODO

• Improve test cases
• Implement more web servers