GoSpeak - Generate REST APIs from Go code

NOTICE: Under development. Seeking early user feedback.

GoSpeak is a simple RPC framework, a lightweight alternative to gRPC and Twirp, where Go code is your protobuf.

//go:generate github.com/golang-cz/gospeak/cmd/gospeak ./
package proto

//go:webrpc golang -server -pkg=server -out=./server/server.gen.go
//go:webrpc golang -client -pkg=client -out=./client/example.gen.go
type ExampleAPI interface {
	Ping(context.Context, *Ping) (*Pong, error)
}

Usage:

$ go get github.com/golang-cz/gospeak/cmd/gospeak@latest
$ go generate
            ExampleAPI => ./server/server.gen.go ✓
            ExampleAPI => ./client/example.gen.go ✓

Language support

GoSpeak uses webrpc-gen tool to generate REST API client & server code using Go templates. The API routes and JSON payload are defined per webrpc specs and can be exported to OpenAPI 3.x (Swagger) documentation.

Server		Client
Go 1.20+	<=>	Go 1.17+
Go 1.20+	<=>	TypeScript
Go 1.20+	<=>	JavaScript (ES6)
Go 1.20+	<=>	OpenAPI 3+ (Swagger documentation)
Go 1.20+	<=>	Any OpenAPI client code generator

Quick example

• 1. Define service API
• 2. Add target language directives
• 3. Generate code
• 4. Mount the API server
• 5. Implement the server business logic
• 6. Use the generated client
• 7. Test your API

1. Define service API

package proto

import "context"

type PetStore interface {
	GetPet(ctx context.Context, ID int64) (pet *Pet, err error)
	ListPets(ctx context.Context) (pets []*Pet, err error)
	CreatePet(ctx context.Context, new *Pet) (pet *Pet, err error)
	UpdatePet(ctx context.Context, ID int64, update *Pet) (pet *Pet, err error)
	DeletePet(ctx context.Context, ID int64) error
}

type Pet struct {
	ID        int64
	Name      string
	Available bool
	PhotoURLs []string
	Tags      []Tag
}

type Tag struct {
	ID   int64
	Name string
}

2. Add target language directives

Generate Go server and Go client code with go:webrpc directives:

+//go:webrpc golang -server -pkg=server -out=./server/server.gen.go
+//go:webrpc golang -client -pkg=client -out=./client/example.gen.go
 type PetStore interface {

Generate TypeScript client and OpenAPI 3.x (Swagger) documentation:

 //go:webrpc golang -server -pkg=server -out=./server/server.gen.go
 //go:webrpc golang -client -pkg=client -out=./client/example.gen.go
+//go:webrpc typescript -client -out=./client/exampleClient.gen.ts
+//go:webrpc openapi -out=./docs/exampleApi.gen.yaml -title=PetStoreAPI
 type PetStore interface {

3. Generate code

Install gospeak and generate the webrpc code.

$ gospeak ./proto/api.go
            PetStore => ./server/server.gen.go ✓
            PetStore => ./client/client.gen.go ✓
            PetStore => ./docs/videoApi.gen.yaml ✓
            PetStore => ./client/videoDashboardClient.gen.ts ✓

NOTE: Alternatively, you can go get github.com/golang-cz/gospeak as your dependency and run go generate against //go:generate github.com/golang-cz/gospeak/cmd/gospeak . directive.

4. Mount the API server

// cmd/petstore/main.go
package main

import "./server"

func main() {
	api := &server.Server{} // implements PetStore interface{}

	handler := server.NewPetStoreServer(api)
	http.ListenAndServe(":8080", handler)
}

5. Implement the server business logic

The generated server code already

• handles incoming REST API requests
• unmarshals JSON request into method argument(s)
• calls your RPC method implementation, ie. `server.GetPet(ctx, 1)``
• marshals return argument(s) into a JSON response

What's left is the business logic. Implement the interface methods:

// rpc/server.go
package rpc

type Server struct {
	/* DB connection, config etc. */
}

// rpc/user.go
package rpc

func (s *Server) GetUser(ctx context.Context, uid string) (user *User, err error) {
	user, err := s.DB.GetUser(ctx, uid)
	if err != nil {
		if errors.Is(err, io.EOF) {
			return nil, Errorf(ErrNotFound, "failed to find user(%v)", uid)
		}
		return nil, WrapError(ErrInternal, err, "failed to fetch user(%v)", uid)
	}

	return user, nil
}

See source code

6. Use the generated client

package main

import "./client"

func main() {
	api := client.NewPetStoreClient("http://localhost:8080", http.DefaultClient)

	pets, err := api.ListPets(ctx)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(pets)
}

7. Test your API

package test

import (
	"testing"
	"./client"
)

func TestAPI(t *testing.T){
	api := client.NewPetStoreClient("http://localhost:8080", http.DefaultClient)

	pets, err := api.ListPets(ctx)
	if err != nil {
		t.Fatal(err)
	}

	t.Log(pets)
}

Enjoy!

..and let us know what you think in discussions.

Authors

• golang.cz
• VojtechVitek

License

MIT license