Yeah, that starts taking you down the path to "serverless" - eg. AWS Lambda. I think iron.io has a fully container-based approach here (I've only used their pre-baked containers though).
An application written purely in client-side code, but that still requires a server-side component is not "server-less".
A "server-less" app is one that literally has no need for it. Just because you aren't in control of the server-provided resources the app depends on, doesn't make it "server-less".
