My recollection of the details is fuzzy, but I think a common solution to this is connection draining. You set up your deploy to bring up the new instance and d

My recollection of the details is fuzzy, but I think a common solution to this is connection draining. You set up your deploy to bring up the new instance and direct all new traffic to that one and then hold the old one open until all sessions/connections end. Can't remember if/how that routing was accomplished in the BEAM (Erlang/Elixir VM). It's definitely possible but you might have to implement it yourself.