Wildcard CORS in RAILS

I searched for an easy solution for a wildcard CORS response in Rails.

I found two ways to do it.
There is that stupid rack-cors gem, which didn't work at all (middleware use, insert before, after..).
And you can build a combination of before_filter (for the headers), a real action in your controller (with no content) which gets called by a route.

I couldn't find a simple solution to drop in my routes. I remembered that routes.rb can execute RACK apps, I tried to search for "rack proc cors routes.rb". Nothing. So I had to do it myself.

Here we go:

if Rails.env.development?
    match "/your/url" => proc { |env| [
      200,
      {
        "Content-Type" => 'text/plain',
        "Access-Control-Allow-Origin" => '*',
        "Access-Control-Allow-Methods" => %w{GET POST PUT DELETE}.join(","),
        "Access-Control-Allow-Headers" => %w{Origin Accept Content-Type X-Requested-With X-CSRF-Token}.join(",")
      },
      ["Hello, world"]
    ]},  via: [:options]
  end

Just replace match "/your/url" with your existing route/url which should support the [OPTIONS] call for the CORS request. You can also use wildcard urls like '/your/*'.
The route is wrapped in Rails.env.development? so it never ever leaks in production :)

I had some static JS content under 0.0.0.0:4567 and needed to call my rails app under 0.0.0.0:3000. So easy to run into a CORS problem.

Enjoy.