tanukirpc

tanukirpc is a practical, fast-developing, type-safe, and easy-to-use RPC/Router library for Go. This library base on go-chi/chi.

Installation

go get -u github.com/mackee/tanukirpc

Usage

This is a simple example of how to use tanukirpc.

package main

import (
	"fmt"
	"net/http"

	"github.com/mackee/tanukirpc"
)

type helloRequest struct {
	Name string `urlparam:"name"`
}

type helloResponse struct {
	Message string `json:"message"`
}

func hello(ctx tanukirpc.Context[struct{}], req helloRequest) (*helloResponse, error) {
	return &helloResponse{
		Message: fmt.Sprintf("Hello, %s!", req.Name),
	}, nil
}

func main() {
	r := tanukirpc.NewRouter(struct{}{})
	r.Get("/hello/{name}", tanukirpc.NewHandler(hello))

	if err := r.ListenAndServe(context.Background(), ":8080"); err != nil {
		fmt.Println(err)
	}
}

Features

• ⭕ Type-safe request/response handler
• ⭕ URL parameter, Query String, JSON, Form, or custom binding
• ⭕ Request validation by go-playground/validator
• ⭕ Custom error handling
• ⭕ Registry injection
  • for a Dependency Injection
• ⭕ A development server command that automatically restarts on file changes
  • use tanukiup command
• ⭕ Generate TypeScript client code
  • use gentypescript command
• ⭕ defer hooks for cleanup
• ⭕ Session management
• ⭕ Authentication flow
  • ⭕ OpenID Connect

Registry injection

Registry injection is unique feature of tanukirpc. You can inject a registry object to the handler function.

Additionally, Registry can be generated for each request. For more details, please refer to _example/simple-registry.

Use case

• Database connection
• Logger
• Authentication information
• Resource binding by path parameter. Examples can be found in _example/todo.

Request binding

tanukirpc supports the following request bindings by default:

• URL parameter (like a /entity/{id} path): use the urlparam struct tag
• Query String: use the query struct tag
• JSON (application/json): use the json struct tag
• Form (application/x-www-form-urlencoded): use the form struct tag
• Raw Body: use the rawbody struct tag with []byte or io.ReadCloser
  • also support naked []byte or io.ReadCloser

If you want to use other bindings, you can implement the tanukirpc.Codec interface and specify it using the tanukirpc.WithCodec option when initializing the router.

tanukirpc.NewRouter(YourRegistry, tanukirpc.WithCodec(yourCodec))

Request validation

tanukirpc automatically validation by go-playground/validator when contains validate struct tag in request struct.

type YourRequest struct {
    Name string `form:"name" validate:"required"`
}

If you want to use custom validation, you can implement the tanukirpc.Validatable interface in your request struct. tanukirpc will call the Validatable.Validate method after binding the request and before calling the handler function.

Error handling

tanukirpc has a default error handler. If you want to use custom error handling, you can implement the tanukirpc.ErrorHooker interface and use this with the tanukirpc.WithErrorHooker option when initializing the router.

Response with Status Code

If you want to return a response with a specific status code, you can use the tanukirpc.WrapErrorWithStatus.

// this handler returns a 404 status code
func notFoundHandler(ctx tanukirpc.Context[struct{}], struct{}) (*struct{}, error) {
    return nil, tanukirpc.WrapErrorWithStatus(http.StatusNotFound, errors.New("not found"))
}

Also, you can use the tanukirpc.ErrorRedirectTo function. This function returns a response with a 3xx status code and a Location header.

// this handler returns a 301 status code
func redirectHandler(ctx tanukirpc.Context[struct{}], struct{}) (*struct{}, error) {
    return nil, tanukirpc.ErrorRedirectTo(http.StatusMovedPermanently, "/new-location")
}

Middleware

You can use tanukirpc with go-chi/chi/middleware or func (http.Handler) http.Handler style middlewares. gorilla/handlers is also included in this.

If you want to use middleware, you can use *Router.Use or *Router.With.

tanukiup command

The tanukiup command is very useful during development. When you start your server via the tanukiup command, it detects file changes, triggers a build, and restarts the server.

Usage

You can use the tanukiup command as follows:

$ go run github.com/mackee/tanukirpc/cmd/tanukiup -dir ./...

• The -dir option specifies the directory to be watched. By appending ... to the end, it recursively includes all subdirectories in the watch scope. If you want to exclude certain directories, use the -ignore-dir option. You can specify multiple directories by providing comma-separated values or by using the option multiple times. By default, the server will restart when files with the .go extension are updated.

• The -addr option allows the tanukiup command to act as a server itself. After building and starting the server application created with tanukirpc, it proxies requests to this process. The application must be started with *tanukirpc.Router.ListenAndServe; otherwise, the -addr option will not function. Only the paths registered with tanukirpc.Router will be proxied to the server application.

• Additionally, there is an option called -catchall-target that can be used in conjunction with -addr. This option allows you to proxy requests for paths that are not registered with tanukirpc.Router to another server address. This is particularly useful when working with a frontend development server (e.g., webpack, vite).

Additionally, it detects the go:generate lines for the gentypescript command mentioned later, and automatically runs them before restarting.

Client code generation

A web application server using tanukirpc can generate client-side code based on the type information of each endpoint.

gentypescript generates client-side code specifically for TypeScript. By using the generated client implementation, you can send and receive API requests with type safety for each endpoint.

To generate the client code, first call genclient.AnalyzeTarget with the router as an argument to clearly define the target router.

Next, add the following go:generate line:

//go:generate go run github.com/mackee/tanukirpc/cmd/gentypescript -out ./frontend/src/client.ts ./

The -out option specifies the output file name. Additionally, append ./ to specify the package to be analyzed.

When you run go generate ./ in the package containing this file, or when you start the server via the aforementioned tanukiup command, the TypeScript client code will be generated.

For more detailed usage, refer to the _example/todo directory.

Defer hooks

tanukirpc supports defer hooks for cleanup. You can register a function to be called after the handler function has been executed.

func (ctx *tanukirpc.Context[struct{}], struct{}) (*struct{}, error) {
    ctx.Defer(func() error {
        // Close the database connection, release resources, logging, enqueue job etc...
    })
    return &struct{}{}, nil
}

Session Management

tanukirpc provides convenient utilities for session management. You can use the gorilla/sessions package or other session management libraries.

To get started, create a session store and wrap it using tanukirpc/auth/gorilla.NewStore.

import (
    "github.com/gorilla/sessions"
    "github.com/mackee/tanukirpc/sessions/gorilla"
    tsessions "github.com/mackee/tanukirpc/sessions"
)

func newStore(secrets []byte) (tsessions.Store, error) {
    sessionStore := sessions.NewCookieStore(secrets)
    store, err := gorilla.NewStore(sessionStore)
    if err != nil {
        return nil, err
    }
    return store, nil
}

In RegistryFactory, you can create a session using the tanukirpc/sessions.Store.

type RegistryFactory struct {
    Store tsessions.Store
}

type Registry struct {
    sessionAccessor tsessions.Accessor
}

func (r *RegistryFactory) NewRegistry(w http.ResponseWriter, req *http.Request) (*Registry, error) {
	accessor, err := r.Store.GetAccessor(req)
	if err != nil {
		return nil, fmt.Errorf("failed to get session accessor: %w", err)
	}

    return &Registry{
        sessionAccessor: accessor,
    }, nil
}

func (r *Registry) Session() tsessions.Accessor {
    return r.sessionAccessor
}

The Registry type implements the tanukirpc/sessions.RegistryWithAccessor interface.

Authentication Flow

tanukirpc supports the OpenID Connect authentication flow. You can use the tanukirpc/auth/oidc.NewHandlers function to create handlers for this flow, which includes a set of handlers to facilitate user authentication.

Requirements

tanukirpc/auth/oidc.Handlers requires a Registry that implements the tanukirpc/sessions.RegistryWithAccessor interface. For more details, refer to the Session Management section.

Usage

oidcAuth := oidc.NewHandlers(
    oauth2Config, // *golang.org/x/oauth2.Config
    provider,     // *github.com/coreos/go-oidc/v3/oidc.Provider
)
router.Route("/auth", func(router *tanukirpc.Router[*Registry]) {
    router.Get("/redirect", tanukirpc.NewHandler(oidcAuth.Redirect))
    router.Get("/callback", tanukirpc.NewHandler(oidcAuth.Callback))
    router.Get("/logout", tanukirpc.NewHandler(oidcAuth.Logout))
})

License

Copyright (c) 2024- mackee

Licensed under MIT License.