When you upload a Ruby application to your domain’s directory and enable Ruby support on the domain, Plesk detects and registers the application. You can then install all necessary gems (Ruby code packages) using Bundler - the utility for tracking and installing the specific versions of gems required by the application (read more at http://bundler.io/), add environment variables, edit the configuration files, and restart the application. For details, refer to Manage Ruby Applications.
To take advantage of this feature, make sure that the following requirements are met:
The Ruby extension must be installed in Plesk. The extension automatically installs two components: Ruby support and Phusion Passenger server. Phusion Passenger is an application server that allows you to load an application and serve the requests to it as fast as possible. It is installed as a module of the Apache or nginx web server. You can find more information at (https://en.wikipedia.org/wiki/Phusion_Passenger).
The complex Ruby applications (for example, the applications based on the Ruby on Rails framework) often require compilation during gems installation. To install such gems in easy manner, the special Tools required for building Ruby gems component should be installed (for details, refer to Adding and Removing Plesk components). This component provides the development libraries required for compilation of the most popular Ruby gems to ensure that Bundler can install gems successfully.
A domain should have a service plan granting the Ruby support management permission.