How to override X-Frame-Options for a controller or action in Rails 4

Question

Rails 4 appears to set a default value of SAMEORIGIN for the X-Frame-Options HTTP response header. This is great for security, but it does not allow for parts of your app to be available in an iframe on a different domain.

You can override the value of X-Frame-Options globally using the config.action_dispatch.default_headers setting:

config.action_dispatch.default_headers['X-Frame-Options'] = "ALLOW-FROM https://apps.facebook.com"

But how do you override it for just a single controller or action?

Answer 1

If you want to remove the header completely, you can create an after_action filter:

class FilesController < ApplicationController
  after_action :allow_iframe, only: :embed

  def embed
  end

private

  def allow_iframe
    response.headers.except! 'X-Frame-Options'
  end
end

Or, of course, you can code the after_action to set the value to something different:

class FacebookController < ApplicationController
  after_action :allow_facebook_iframe

private

  def allow_facebook_iframe
    response.headers['X-Frame-Options'] = 'ALLOW-FROM https://apps.facebook.com'
  end
end

Note that you need to clear your cache in certain browsers (Chrome for me) while debugging this.