A classic martini web server that demonstrates using middleware and route handlers to keep authentication and authorization code DRY.

classicMartini.go

package main

import (
	"github.com/go-martini/martini"
)

func main() {
	// Create a new Martini server
	m := martini.New()
	
	// Add middleware that logs incoming requests, and how long they take to handle
	m.Use(martini.Logger())
	
	// Add middleware which recovers from any panics, preventing the whole server from
	// crashing over one bad request.
	m.Use(martini.Recovery())
	
	// Creates a new martini router and sets it as the handler that runs after all middleware
	r := martini.NewRouter()
	m.Action(r.Handle)
	
	// Everything so far could be replaced by one line: m := martini.Classic()

	// Register middleware which authenticates the client
	m.Use(Authentication)

	// Public route
	r.Get("/", func() string {
		return "Hello World!"
	})

	// Private route
	r.Get("/secret", Authorization("secret access"), func() string {
		return "Hello Secret Agent!"
	})

	// Start the server
	m.Run()
}

// Type which, through reflection, Martini uses to dependency inject the user
// found by the Authentication middleware
type User interface{}

// Identifies the user for the request
func Authentication(c martini.Context) {
  // ...
  c.MapTo(user, (*User)(nil))
}

// Creates a handler function for checking that the user has specific access
func Authorization(access string) func() {
	return func(u User) {
		// ...
	}
}