According to the Unicorn docs, there are different binaries for Rails apps and other Rack apps:
non-Rails Rack applications
In APP_ROOT, run:
unicorn
for Rails applications (should work for all 1.2 or later versions)
In RAILS_ROOT, run:
unicorn_rails
They seem to also take the same command-line parameters. But Rails is built on top of rack, so I don't understand why this dichotomy is required. Is there any reason you can't just use unicorn
for Rails apps?
From the unicorn docs,
http://unicorn.bogomips.org/unicorn_rails_1.html
So, no, you don't need to use it at all.
It's worth pointing out that Rails only made the transition to Rack in late version 2 (I forget). So, when Unicorn first got released there were probably still a bunch of apps that had to be supported.