A simple Sinatra extension to enable Cross Domain Resource Sharing (CORS) To see more on cross domain resource sharing, see https://developer.mozilla.org/En/HTTP_access_control

gem "sinatra-cross_origin", "~> 0.3.1"

To enable cross origin requests for all routes:

require 'sinatra'
require 'sinatra/cross_origin'

configure do
  enable :cross_origin
end

To only enable cross origin requests for certain routes:

get '/cross_origin' do
  cross_origin
  "This is available to cross-origin javascripts"
end

If you're using a modular application, remember to register this extension:

register Sinatra::CrossOrigin

You can set global options via the normal Sinatra set method:

set :allow_origin, :any
set :allow_methods, [:get, :post, :options]
set :allow_credentials, true
set :max_age, "1728000"
set :expose_headers, ['Content-Type']

You can change configuration options on the fly within routes with:

get '/custom' do
  cross_origin :allow_origin => 'http://example.com',
    :allow_methods => [:get],
    :allow_credentials => false,
    :max_age => "60"

  "My custom cross origin response"
end

Many browsers send an OPTIONS request to a server before performing a CORS request (this is part of the specification for CORS ). These sorts of requests are called preflight requests. Without a valid response to an OPTIONS request, a browser may refuse to make a CORS request (and complain that the CORS request violates the same-origin policy).

Currently, this gem does not properly respond to OPTIONS requests. See this issue. You may have to add code like this in order to make your app properly respond to OPTIONS requests:

options "*" do
  response.headers["Allow"] = "HEAD,GET,PUT,POST,DELETE,OPTIONS"
 
  response.headers["Access-Control-Allow-Headers"] = "X-Requested-With, X-HTTP-Method-Override, Content-Type, Cache-Control, Accept"
 
  200
end

Copyright (c) 2007, 2008, 2009 Brit Gardner

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:

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