This is a ruby port of Apple's own java-based Autoingest tool, that downloads app sales reports from iTunes Connect. It is a slightly more ruby-friendly fork of wjlafrance's take on the app.
In order to grab daily reports from the day before, configure your account by creating config.yml and running ruby autoingestion.rb. Output will be saved in the output directory. Processing the output is up to you.
You can automate this process by adding this to your favorite version of cron.