Excellent approach. I really appreciate how the author adapted his article after getting constructive feedback. The iptables trick is very nice. The kind of thing you think to yourself: “this is obvious!”, but only after finding out about it.
I think there is still a living vein of old school KISS deployment & management of production applications in the Erlang/Elixir world. I know once upon a time Whatsapp used to do their deployments with a bash script, can anyone corroborate what the state is currently? (or correct me if I’m repeating BEAMer urban legends?)
At a previous job (big chat system), we served the entire world on a cluster of 4 beefy EC2 instances and ansible deployments of OTP release bundles.
One more thought: although it would conflict with the ‘zero cost’ premise of the article, plugging in sqlite+litestream and dropping postgres would reduce the mental overhead of managing Postgres permissions and security.