Update 10/26/2023: The Rails experimental support has been broken for a while. It has been removed in Jets v5 to prepare for a version of Rails support that will be container based. There is currently no timeline. These docs are only kept around for posterity.
Jets supports deploying Rails applications with a few approaches that are experimental.
Mount Rails App?
Rails is also rack compatible, so you may wonder if you can mount a Rails app with Jets routes mount support. Mounting a Rails app is not currently recommended. Some thoughts on this here: Mounting Rails Apps