Lion

Lion is a fast HTTP router for Go with support for middlewares for building modern scalable modular REST APIs.

Features

Context-Aware: Lion uses the de-facto standard net/Context for storing route params and sharing variables between middlewares and HTTP handlers. It could be integrated in the standard library for Go 1.7 in 2016.
Modular: You can define your own modules to easily build a scalable architecture
REST friendly: You can define modules to groups http resources together.
Zero allocations: Lion generates zero garbage*.

Install/Update
Hello World
Getting started with modules and resources
Handlers
Middlewares
Resources
Examples

Install/Update

$ go get -u github.com/celrenheit/lion

Hello World

package main

import (
    "fmt"
    "net/http"

    "github.com/celrenheit/lion"
    "golang.org/x/net/context"
)

func Home(c context.Context, w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Home")
}

func Hello(c context.Context, w http.ResponseWriter, r *http.Request) {
    name := lion.Param(c, "name")
    fmt.Fprintf(w, "Hello "+name)
}

func main() {
    l := lion.Classic()
    l.GetFunc("/", Home)
    l.GetFunc("/hello/:name", Hello)
    l.Run()
}

Try it yourself by running the following command from the current directory:

$ go run examples/hello/hello.go

Getting started with modules and resources

We are going to build a sample products listing REST api (without database handling to keep it simple):

func main() {
    l := lion.Classic()
    api := l.Group("/api")
    api.Module(Products{})
    l.Run()
}

// Products module is accessible at url: /api/products
// It handles getting a list of products or creating a new product
type Products struct{}

func (p Products) Base() string {
    return "/products"
}

func (p Products) Get(c context.Context, w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Fetching all products")
}

func (p Products) Post(c context.Context, w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Creating a new product")
}

func (p Products) Routes(r *lion.Router) {
    // Defining a resource for getting, editing and deleting a single product
    r.Resource("/:id", OneProduct{})
}

// OneProduct resource is accessible at url: /api/products/:id
// It handles getting, editing and deleting a single product
type OneProduct struct{}

func (p OneProduct) Get(c context.Context, w http.ResponseWriter, r *http.Request) {
    id := lion.Param(c, "id")
    fmt.Fprintf(w, "Getting product: %s", id)
}

func (p OneProduct) Put(c context.Context, w http.ResponseWriter, r *http.Request) {
    id := lion.Param(c, "id")
    fmt.Fprintf(w, "Updating article: %s", id)
}

func (p OneProduct) Delete(c context.Context, w http.ResponseWriter, r *http.Request) {
    id := lion.Param(c, "id")
    fmt.Fprintf(w, "Deleting article: %s", id)
}

Try it yourself. Run:

$ go run examples/modular-hello/modular-hello.go

Open your web browser to http://localhost:3000/api/products or http://localhost:3000/api/products/123. You should see "Fetching all products" or "Getting product: 123".

Handlers

Handlers should implement the Handler interface:

type Handler interface {
    ServeHTTPC(context.Context, http.ResponseWriter, *http.Request)
}

Using Handlers

l.Get("/get", get)
l.Post("/post", post)
l.Put("/put", put)
l.Delete("/delete", delete)

Using HandlerFuncs

HandlerFuncs shoud have this function signature:

func handlerFunc(c context.Context, w http.ResponseWriter, r *http.Request)  {
  fmt.Fprintf(w, "Hi!")
}

l.GetFunc("/get", handlerFunc)
l.PostFunc("/post", handlerFunc)
l.PutFunc("/put", handlerFunc)
l.DeleteFunc("/delete", handlerFunc)

Using native http.Handler

type nativehandler struct {}

func (_ nativehandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {

}

l.GetH("/somepath", nativehandler{})
l.PostH("/somepath", nativehandler{})
l.PutH("/somepath", nativehandler{})
l.DeleteH("/somepath", nativehandler{})

Using native http.Handler using lion.Wrap()

Note: using native http handler you cannot access url params.

func main() {
    l := lion.New()
    l.Get("/somepath", lion.Wrap(nativehandler{}))
}

Using native http.Handler using lion.WrapFunc()

func getHandlerFunc(w http.ResponseWriter, r *http.Request) {

}

func main() {
    l := lion.New()
    l.Get("/somepath", lion.WrapFunc(getHandlerFunc))
}

Middlewares

Middlewares should implement the Middleware interface:

type Middleware interface {
    ServeNext(Handler) Handler
}

The ServeNext function accepts a Handler and returns a Handler.

You can also use MiddlewareFuncs. For example:

func middlewareFunc(next Handler) Handler  {
    return next
}

You can also use Negroni middlewares by registering them using:

l := lion.New()
l.UseNegroni(negroni.NewRecovery())
l.Run()

Resources

You can define a resource to represent a REST, CRUD api resource. You define global middlewares using Uses() method. For defining custom middlewares for each http method, you have to create a function which name is composed of the http method suffixed by "Middlewares". For example, if you want to define middlewares for the Get method you will have to create a method called: GetMiddlewares().

A resource is defined by the following methods. Everything is optional:

// Global middlewares for the resource (Optional)
Uses() Middlewares

// Middlewares for the http methods (Optional)
GetMiddlewares() Middlewares
PostMiddlewares() Middlewares
PutMiddlewares() Middlewares
DeleteMiddlewares() Middlewares


// HandlerFuncs for each HTTP Methods (Optional)
Get(c context.Context, w http.ResponseWriter, r *http.Request)
Post(c context.Context, w http.ResponseWriter, r *http.Request)
Put(c context.Context, w http.ResponseWriter, r *http.Request)
Delete(c context.Context, w http.ResponseWriter, r *http.Request)

Example:

package main

type todolist struct{}

func (t todolist) Uses() lion.Middlewares {
    return lion.Middlewares{lion.NewLogger()}
}

func (t todolist) Get(c context.Context, w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "getting todos")
}

func main() {
    l := lion.New()
    l.Resource("/todos", todolist{})
    l.Run()
}

Modules

Modules are a way to modularize an api which can then define submodules, subresources and custom routes. A module is defined by the following methods:

// Required: Base url pattern of the module
Base() string

// Routes accepts a Router instance. This method is used to define the routes of this module.
// Each routes defined are relative to the Base() url pattern
Routes(*Router)

// Optional: Requires named middlewares. Refer to Named Middlewares section
Requires() []string

package main

type api struct{}

// Required: Base url
func (t api) Base() string { return "/api" }

// Required: Here you can declare sub-resources, submodules and custom routes.
func (t api) Routes(r *lion.Router) {
    r.Module(v1{})
    r.Get("/custom", t.CustomRoute)
}

// Optional: Attach Get method to this Module.
// ====> A Module is also a Resource.
func (t api) Get(c context.Context, w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "This also a resource accessible at http://localhost:3000/api")
}

// Optional: Defining custom routes
func (t api) CustomRoute(c context.Context, w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "This a custom route for this module http://localhost:3000/api/")
}

func main() {
    l := lion.New()
    // Registering the module
    l.Module(api{})
    l.Run()
}

Examples

Using GET, POST, PUT, DELETE http methods

l := lion.Classic()

// Using Handlers
l.Get("/get", get)
l.Post("/post", post)
l.Put("/put", put)
l.Delete("/delete", delete)

// Using functions
l.GetFunc("/get", getFunc)
l.PostFunc("/post", postFunc)
l.PutFunc("/put", putFunc)
l.DeleteFunc("/delete", deleteFunc)

l.Run()

Using middlewares

func main() {
    l := lion.Classic()

    // Using middleware
    l.Use(lion.NewLogger())

    // Using middleware functions
    l.UseFunc(someMiddlewareFunc)

    l.GetFunc("/hello/:name", Hello)

    l.Run()
}

Group routes by a base path

l := lion.Classic()
api := l.Group("/api")

v1 := l.Group("/v1")
v1.GetFunc("/somepath", gettingFromV1)

v2 := l.Group("/v2")
v2.GetFunc("/somepath", gettingFromV2)

l.Run()

Mouting a router into a base path

l := lion.Classic()

sub := lion.New()
sub.GetFunc("/somepath", getting)


l.Mount("/api", sub)

Default middlewares

lion.Classic() creates a router with default middlewares (Recovery, RealIP, Logger, Static). If you wish to create a blank router without any middlewares you can use lion.New().

func main()  {
    // This a no middlewares registered
    l := lion.New()
    l.Use(lion.NewLogger())

    l.GetFunc("/hello/:name", Hello)

    l.Run()
}

Custom Middlewares

Custom middlewares should implement the Middleware interface:

type Middleware interface {
    ServeNext(Handler) Handler
}

You can also make MiddlewareFuncs to use using .UseFunc() method. It has to accept a Handler and return a Handler:

func(next Handler) Handler

Custom Logger example

type logger struct{}

func (*logger) ServeNext(next lion.Handler) lion.Handler {
    return lion.HandlerFunc(func(c context.Context, w http.ResponseWriter, r *http.Request) {
        start := time.Now()

        next.ServeHTTPC(c, w, r)

        fmt.Printf("Served %s in %s\n", r.URL.Path, time.Since(start))
    })
}

Then in the main function you can use the middleware using:

l := lion.New()

l.Use(&logger{})
l.GetFunc("/hello/:name", Hello)
l.Run()

Benchmarks

Without path.Clean

BenchmarkLion_Param         10000000           164 ns/op           0 B/op          0 allocs/op
BenchmarkLion_Param5         5000000           372 ns/op           0 B/op          0 allocs/op
BenchmarkLion_Param20        1000000          1080 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParamWrite    10000000           180 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GithubStatic  10000000           160 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GithubParam    5000000           359 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GithubAll        30000         62888 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlusStatic   20000000           104 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlusParam    10000000           182 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlus2Params   5000000           286 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlusAll        500000          3227 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParseStatic   10000000           123 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParseParam    10000000           145 ns/op           0 B/op          0 allocs/op
BenchmarkLion_Parse2Params  10000000           212 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParseAll        300000          5242 ns/op           0 B/op          0 allocs/op
BenchmarkLion_StaticAll        50000         37998 ns/op           0 B/op          0 allocs/op

With path.Clean

BenchmarkLion_Param         10000000           227 ns/op           0 B/op          0 allocs/op
BenchmarkLion_Param5         3000000           427 ns/op           0 B/op          0 allocs/op
BenchmarkLion_Param20        1000000          1321 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParamWrite     5000000           256 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GithubStatic  10000000           214 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GithubParam    3000000           445 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GithubAll        20000         88664 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlusStatic   10000000           122 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlusParam     5000000           381 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlus2Params   5000000           409 ns/op           0 B/op          0 allocs/op
BenchmarkLion_GPlusAll        500000          3952 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParseStatic   10000000           146 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParseParam    10000000           187 ns/op           0 B/op          0 allocs/op
BenchmarkLion_Parse2Params   5000000           314 ns/op           0 B/op          0 allocs/op
BenchmarkLion_ParseAll        200000          7857 ns/op           0 B/op          0 allocs/op
BenchmarkLion_StaticAll        30000         56170 ns/op          96 B/op          8 allocs/op

A more in depth benchmark with a comparison with other frameworks is coming soon.

License

https://github.com/celrenheit/lion/blob/master/LICENSE

Todo

Better static file handling
More documentation

Credits

@codegangsta for https://github.com/codegangsta/negroni
- Static and Recovery middlewares are taken from Negroni
@zenazn for https://github.com/zenazn/goji/
- RealIP middleware is taken from goji
@pkieltyka for https://github.com/pressly/chi and @armon for https://github.com/armon/go-radix
- Radix tree matcher implementation is inspired by both of these packages
https://github.com/gin-gonic/gin for ResponseWriter and Logger inspiration

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.gitignore	Push to github	Mar 20, 2016
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LICENSE	Push to github	Mar 19, 2016
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context.go	Push to github	Mar 19, 2016
lion.go	Push to github	Mar 19, 2016
matcher.go	Push to github	Mar 19, 2016
middlewares.go	Improve documentation for Classic()	Mar 20, 2016
module.go	Push to github	Mar 19, 2016
module_test.go	Push to github	Mar 19, 2016
resource.go	Push to github	Mar 19, 2016
resource_test.go	Push to github	Mar 19, 2016
response_writer.go	Push to github	Mar 19, 2016
router.go	Added support for HEAD, TRACE, OPTIONS, CONNECT and PATCH http methods	Mar 21, 2016
router_test.go	Push to github	Mar 19, 2016
tree.go	Push to github	Mar 19, 2016
utils.go	Push to github	Mar 19, 2016

celrenheit/lion

README.md