Rack::API

Create web app APIs that respond to one or more formats using an elegant DSL.

Installation

gem install rack-api

Usage

Basic example

Rack::API.app do
  prefix "api"

  version :v1 do
    get "users(.:format)" do
      User.all
    end

    get "users/:id(.:format)" do
      User.find(params[:id])
    end
  end
end

Starting a server with Rack

To run Rack::API through Rack (‘config.ru`), you just need to provide your class. If you’re using the DSL format, you need to provide the Rack::API class.

require "rack/api"
run Rack::API

Otherwise, just provide your custom class.

require "rack/api"

class MyApp < Rack::API
  get "/" do
    {:message => "Hello World"}
  end
end

run MyApp

Now, you can execute ‘rackup` and your app will be available through the 9292 port.

$ rackup -p 3000
[2011-08-05 20:38:11] INFO  WEBrick 1.3.1
[2011-08-05 20:38:11] INFO  ruby 1.9.3 (2011-07-31) [x86_64-darwin11.0.0]
[2011-08-05 20:38:11] INFO  WEBrick::HTTPServer#start: pid=95318 port=3000

$ curl localhost:3000
{"message" => "Hello World"}

You can also run other application servers that recognize Rack, like Thin.

$ thin -R config.ru start
>> Thin web server (v1.2.11 codename Bat-Shit Crazy)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:3000, CTRL+C to stop

$ curl localhost:9292
{"message" => "Hello World"}

Rails Integration

First, set up your Gemfile like this:

gem "rack-api", "~> 1.0", :require => "rack/api"

Create your API somewhere. In this example, we’ll add it to lib/api.rb.

Rack::API.app do
  prefix "api"

  version :v1 do
    get "status(.:format)" do
      {:success => true, :time => Time.now}
    end
  end
end

Load this file somehow. I’d create a config/initializers/dependencies.rb with something like

require "lib/api"

Finally, you can set up the API routing. Open config/routes.rb and add the following line:

mount Rack::API => "/"

If you define your API by inheriting from the Rack::API class, remember to mount your class instead.

mount MyAPI => "/"

For additional examples, see github.com/fnando/rack-api/tree/master/examples.

Using RSpec with Rack::API

You can easily test Rack::API apps by using Rack::Test. This applies to both RSpec and Test Unit. See what you need to do if you want to use it with RSpec.

First, open your spec/spec_helper.rb and add something like this:

require "rspec"
require "rack/test"

RSpec.configure do |config|
  config.include Rack::Test::Methods
end

Then you can go to your spec file, say, spec/api_spec.rb. You need to define a helper method called app, which will point to your Rack::API (the class itself or your own class).

require "spec_helper"

describe Rack::API do
  # Remember to use your own class if you
  # inherited from Rack::API
  def app; Rack::API; end

  it "renders status page" do
    get "/api/v1/status"
    last_response.body.should == {:status => "running"}.to_json
    last_response.status.should == 200
  end
end

If you want to do expectations over basic authentication, you’ll have some like this:

require "spec_helper"

describe Rack::API do
  def basic_auth(username, password)
    "Basic " + Base64.encode64("#{username}:#{password}")
  end

  it "requires authentication" do
    get "/api/v1/status"
    last_response.status.should == 401
  end

  it "grants access" do
    get "/api/v1/status", {"HTTP_AUTHORIZATION" => basic_auth("john", "test")}
    last_response.status.should == 200
  end
end

To reduce duplication, you can move both basic_auth and app methods to a module, which will be included on RSpec.

RSpec.configure do |config|
  config.include Rack::Test::Methods
  config.include Helpers
end

Your Helpers module may look like this:

module Helpers
  def app
    Rack::API
  end

  def basic_auth(username, password)
    "Basic " + Base64.encode64("#{username}:#{password}")
  end
end

Helpers

Every Rack::API action has several helper methods available through the Rack::API::Controller class. Here’s some of them:

logger

Logs specified message to the STDOUT.

get "/" do
  logger.info "Hello index page!"
  {}
end

headers

Define custom headers that will be sent to the client.

get "/" do
  headers["X-Awesome"] = "U R Awesome"
  {}
end

params

Return current request parameters.

get "/" do
  {:message => "Hello #{params[:name]}"}
end

request

Return an object relative to the current request.

credentials

This method will return an array container both username and password if client sent Basic Authentication headers.

get "/" do
  user, pass = credentials
  {:message => "Hello #{user}"}
end

url_for

Build an URL by merging segments, default URL options and hash with parameters.

Rack::API.app do
  default_url_options :host => "example.com", :protocol => "https"

  version "v1" do
    get "/" do
      {:url => url_for(:users, User.find(params[:id])), :format => :json}
    end
  end
end

Useful middlewares

Rack::API::Middleware::SSL

This middleware will accept only HTTPS requests. Any request over HTTP will be dropped.

Rack::API.app do
  use Rack::API::Middleware::SSL
end

Rack::API::Middleware::Limit

This middleware will limit access to API based on requests per hour. It requires a Redis connection.

Rack::API.app do
  # Use the default settings.
  # Will accept 60 requests/hour limited by IP address (REMOTE_ADDR)
  use Rack::API::Middleware::Limit, :with => Redis.new
end

Other usages:

# Set custom limit/hour.
# Will accept ± 1 request/second.
use Rack::API::Middleware::Limit, :with => $redis, :limit => 3600

# Set custom string key.
# Will limit by something like env["X-Forwarded-For"].
use Rack::API::Middleware::Limit, :with => $redis, :key => "X-Forwarded-For"

# Set custom block key.
# Will limit by credential (Basic Auth).
Rack::API.app do
  basic_auth do |user, pass|
    User.authorize(user, pass)
  end

  use Rack::API::Middleware::Limit, :with => $redis, :key => proc {|env|
    request = Rack::Auth::Basic::Request.new(env)
    request.credentials[0]
  }
end

Maintainer

• Nando Vieira (nandovieira.com.br)

License

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.