ratelimit.rb

class ApplicationController < ActionController::Base
  ...

  before_filter :throttle

  def throttle
    client_ip = request.env["REMOTE_ADDR"]
    key = "count:#{client_ip}"
    count = REDIS.get(key)

    unless count
      REDIS.set(key, 0)
      REDIS.expire(key, THROTTLE_TIME_WINDOW)
      return true
    end

    if count.to_i >= THROTTLE_MAX_REQUESTS
      render :status => 429, :json => {:message => "You have fired too many requests. Please wait for some time."}
      return
    end
    REDIS.incr(key)
    true
  end

  ...
end