How to set access-control-allow-origin in webrick under rails?

I have written a small rails app to serve up content to another site via xmlhttprequests that will be operating from another domain (it will not be possible to get them running on the same server). I understand I will need to set access-control-allow-origin on my rails server to allow the requesting web page to access this material.

It seems fairly well documented how to do this with Apache and this is probably the server I will use once I deploy the site. While I am developing though I hope to just use webrick as I am used to doing with rails. Is there a way of configuring webrick to provide the appropriate http header within rails?


If you're on Rails 2 just add this to your application contoller.

before_filter :set_access

def set_access
  @response.headers["Access-Control-Allow-Origin"] = "*"

Obviously changing "*" to something a little less open would be a good idea.

Rails 4 (

In config/application.rb:

  'Access-Control-Allow-Origin' => '*',
  'Access-Control-Request-Method' => '*'

Rails 3.1

class ApplicationController < ActionController::Base
  after_filter :set_access_control_headers

  def set_access_control_headers
    headers['Access-Control-Allow-Origin'] = '*'
    headers['Access-Control-Request-Method'] = '*'

Rails 3.1 - using a controller after_filter did not work for me so I added a custom middleware instead:

In app/middleware/cors_middleware.rb:

# For icons to work in Firefox with CDN
class CorsMiddleware
  def initialize(app)
    @app = app

  def call(env)
    status, headers, body =
    cors_headers = headers.merge({
      'Access-Control-Allow-Origin' => '*',
      'Access-Control-Request-Method' => '*'        
    [status, cors_headers, body]

In config/application.rb:

require File.join(Rails.root, "app", "middleware", "cors_middleware")
config.middleware.insert_before ActionDispatch::Static, CorsMiddleware # Need it early in the chain to work for assets

Rails 2.3.8

before_filter :allow_cross_domain_access
def allow_cross_domain_access
  response.headers["Access-Control-Allow-Origin"] = "*"
  response.headers["Access-Control-Allow-Methods"] = "*"

In case you want the solution as a Rack middleware gem:

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