code.pfad.fr/risefront is a package for gracefully upgrading the server behing a tcp connection with zero-downtime (without disturbing running transfers or dropping incoming requests).
Inspired by overseer, but re-engineered to also work on windows!
The name is meant to be the opposite of fallback (since it switches to a new executable when asked to do so).
When you start multiple instances of a program wrapped in risefront:
- the first one (the parent
o) will actually listen to the addresses and callRun - when a second instance (child
A) is started, it detects that a parent is already running- it creates some random sockets to locally listen to
- it informs the parent, that it wants to take over
- it calls
Runwith those "proxy listeners" - from now on, the parent will forward all new connections to those "proxy listeners"
- if a third instance is started (child
B), the same steps happen and the second instance (childA) will exit after handling its last request