In theory, yes. In real life, usually not.
Many shared hosting providers claim to support Ruby on Rails, and have it available to be installed. But that doesn’t mean it will actually work well.
1) One problem is package management. Ruby on Rails depends on a complex automated dependency management system called the Ruby Gems system. This system makes sure that you have all the libraries, scripts, and third-party modules you might need installed are actually installed, and upgraded to the correct version. It’s magical.
2) It also just doesn’t work very well on shared hosting. Many of the shared hosting providers claim that it does, but after reading through too many help articles and forum postings, one starts to get the feeling that very few people have managed to deploy it successfully.
3) Another problem with Ruby on Rails and shared hosting is that Rails consumes a lot of resources, compared with other apps, like WordPress or Drupal. This makes the limited resource pool of (even an unlimited) shared hosting plan unlikely to keep up, especially as traffic and user engagement increases.
4) While there are other potential problems (server configuration, workflow management, automated testing), the biggest problem with Ruby on Rails in a shared hosting environment is really tied to the essential nature of Ruby on Rails and shared hosting.
5) Rails was designed, and is primarily used, to build SaaS (software as a service) applications. Shared hosting is designed to put up personal blogs and small business websites. The level of resource allocation, the types of access granted, the whole configuration of the shared hosting server as well as the tools and interfaces presented to customers are all geared toward mostly non-tech-savvy blogger or business owner.
So, even when you can run Rails on a shared hosting environment, you are almost certainly better off using VPS hosting.
