I used this architecture myself for a while, but I don't think I would implement a new project in terms of it at this point. Given a caching reverse-proxy like CloudFlare, there's no disadvantage in serving your client from the app itself. Meanwhile, you get the advantage of being able to test the server during development by just hitting the single ip:port it's running on—and have your automated testing do the same with subrequests, by using the Host header from the request context—without having to make all your test-harness code "infrastructure-aware", teaching it about ports and figuring out ways to pass them in and route them through Docker and map them to domains instead of ports in production and such.

I'm just starting out in Javascript development and have been struggling with build system - how do you achieve cache busting hashes, etc which are necessary to use for a CDN?

We are using webpack and it seems hard to do it.

I highly recommend surge.sh for easy static hosting--their cache-busting strategy is explained here:

https://surge.sh/help/using-lucid-caching-automatically

we use cloudfront and nginx for most of our infrastructure - kinda hard to move to surge right now.

ETags is not viable for this kind of a setup - it pretty much means triggering a nginx reload which is what a cache-busting signature avoids.