Its a pain to code. I’ve done it, and I hated every second of it. Keeping data in sync with dynamic data in near real-time is terrible.

I wrote the CDN in Go, with Redis and a smaller go-powered daemon to retrieve assets every 20 seconds, sync them to a local storage drive, and after 5 days retrieve again - or, if there is no requests within 48 hours, clear the unused items.

Then I setup a system that if one edge requests an “unpopular” file, it’ll ping a simple REST API and have all the other edges pull that file, this allowing the edges to stay “one step ahead” of the user load