[dewey]

> The Ruby on Rails stack may shine with this.

I would guess they just give you a Docker container, otherwise supporting different configurations and host machines sounds like too much of a hassle. Even some libraries shipping with the OS could influence the behaviour outside of pinned gems.

[giobox]

Exactly this - if a web app, it should be offered primarily as a container image for self-hosting support - the age of <insert specific program runtime here> artifacts that the customer installs and runs on an installation of said specific runtime are almost long gone. As a customer, I'd even question why I wasn't handed a container image if they tried to ship me build artifacts and a runtime of some kind.