SavantHosting

Install using gem 'savant-hosting', :github => 'savant-code/savant-hosting', :branch => 'master'.

Then ensure your routes.rb looks like this:

require 'savant-hosting'

Rails.application.routes.draw do
  mount SavantHosting::Engine, at: '/'
end

You'll need to setup Devise on the host app as well:

Add gem "devise" to your Gemfile.

Run bundle exec rails g devise User in your wrapper app's directory.

Finally, the application.html.erb can be emptied and replace with: <%= render 'shared/application' %>