Heroku used to do three magical configuration steps for Rails 3 applications that no longer work with Rails 4 apps due to the removal of support for
vendor/plugins. With the
rails_12factor gem for Rails 4 apps they only added two magical steps back.
The two they added back are:
- Redirecting all logs to STDOUT
The one they missed is setting
x_sendfile_header to nil. Not every Rails app has the
x_sendfile_header setting set to a non-nil value. But for those that do, their static asset serving on Heroku will not work without a config file change; even if they include the
rails_12factor gem in their Gemfile.
I submitted a pull request, I guess we'll see if anything comes of it.