tl;dr – the source is here
Here’s how I mount a Grape API on Rack and also serve static pages. Most useful for building a service with documentation.
Setup bundler with the required gems. I am using the next version of Grape (frontier branch and the next version of rack-contrib which contains Rack::TryStatic that we’re going to want to use).
- source "http://rubygems.org"
- gem "rack", "1.3.5"
- gem "rack-contrib", :git => "https://github.com/rack/rack-contrib.git", :require => "rack/contrib"
- gem "grape", :git => "http://github.com/intridea/grape.git", :branch => "frontier"
Static content goes to a new public folder, for example public/index.html.
Our application will need to boot with all these gems, we’ll do it Rails-style by starting with a config/boot.rb file. It brings in Bundler.
- require 'rubygems'
- require 'bundler/setup'
Lets define our Acme Grape API that will have a system resource that answers ping requests with “pong”. This goes into api/api.rb.
- module Acme
- class API < Grape::API
- version 'v1', :using => :header, :vendor => 'acme', :format => :json
- resource :system do
- desc "Returns pong."
- get :ping do
The application requires Bundler, all the gems in Gemfile and our API. Lets define it in config/application.rb.
- require File.expand_path('../boot', __FILE__)
- Bundler.require :default, ENV['RACK_ENV']
- require File.expand_path('../../api/api', __FILE__)
Note the odd File.expand_path construct, borrowed from Rails, - it translates a relative path to the current file into an absolute path, there’re allowing us to run the application from any directory – useful for hosting where you never know who boots the application.
Continuing to borrow from Rails, we will want different environments (development, production, etc.), so it’s a good idea to keep things organized. Setup the environment in config/environment.rb and then load the application.
- ENV['RACK_ENV'] ||= :test
- require File.expand_path('../application', __FILE__)
Finally, we need to “rackup” this whole thing in config.ru. We will use Rack::TryStatic to serve static pages when available and pass through to the Acme API otherwise.
- require File.expand_path('../config/environment', __FILE__)
- use Rack::TryStatic,
- :root => File.expand_path('../public', __FILE__),
- :urls => %w[/], :try => ['.html', 'index.html', '/index.html']
- run Acme::API
Run the application with bundle exec rackup.
Full source on Github.