How can I specify the order that before_filters are executed?

If you refer http://api.rubyonrails.org/v2.3.8/classes/ActionController/Filters/ClassMethods.html, there is a subheading called "Filter chain ordering", here is the example code from that:

class ShoppingController < ActionController::Base
    before_filter :verify_open_shop

class CheckoutController < ShoppingController
    prepend_before_filter :ensure_items_in_cart, :ensure_items_in_stock

According to the explanation:

The filter chain for the CheckoutController is now :ensure_items_in_cart, :ensure_items_in_stock, :verify_open_shop.

So you can explicitly give the order of the filter chain like that.

Before_filter Order in Rails http://b2.broom9.com/?p=806

Filter chain ordering http://rails.rubyonrails.org/classes/ActionController/Filters/ClassMethods.html

If you need guarantee order, you may do this:

before_filter :fn3

def fn3
  fn1
  fn2
end