Ruby is installed on all DreamHost servers. The default versions on different server types are listed below.
All shared servers run version 2.5.1.
New VPS machines purchased after March 2021 running Debian Buster run 2.5.5.
All Dedicated Servers purchased after March 2020 run version 2.5.1.
Ruby on Shared Hosting
Due to the amount of memory Ruby on Rails may use, it's not recommended to run an app on Shared Hosting. You will most likely be hit the shared server's memory limits.
Installing a current version of Ruby
Running a Ruby app is only recommended on a VPS or Dedicated Server. On those servers, you can install any version you like with Ruby Version Manager.