I'd have picked elixir... Much better concurrency and distribution support. SSH is built into the (erlang) standard lib, really fantastic support for templating via EEx (if you're using libvirt, e.g.). Easy to deploy as an on-metal or containerized platform using releases. Ruby deployment dependency management can be tricky unless you have a way to isolate from the host (containers e.g.) but that's not the best for being a hypervisor.
They're not a hypervisor, though. They provide a control plane that uses one via ssh. Choosing to deploy outside containers at this point in time should in my opinion be a last resort almost irrespective of what you're deploying; if the surface you interact with the host is so complex you can't grant access with granularity to a container without it becoming problematic (or at the very least via a tool providing similar levels of isolation using namespaces), chances are you have a bigger problem.
I've considered at various points (but not with deep seriousness I admit), typescript, julia, scala, swift. You might notice all of these have a REPL in common. Elixir might be a reasonable alternative, but not one I exercised here. In areas I wanted to take risk, I had some other stuff going on.
uh just fyi: Elixir's repl is the most powerful of all of them, as it gives you incredible introspection. With care you can attach a repl to a remote running program (in prod, if you take appropriate precautions) and be able to diagnose the running state of your program quite effectively -- like you can examine the tail call state of any given process.
> With care you can attach a repl to a remote running program
That's good, but it's also table stakes. Drb (in the standard library) lets you remote access any Ruby object, so if you want a remote REPL, it's is simply a case of injecting a Drb server. Hence e.g. pry-remote which remotes the Pry REPL, but you can also then remote any already existing object in any running application.
I mean the equivalent is also possible out of the box Erlang VM. Without having to install sidecar servers or monkey patching objects with potentially spooky action at a distance.
Erlang, from day 1, was designed to be logged in to remotely. No other system is remotely close to the sophistication that Erlang (and as a result elixir) has in this regard
