Are there other applications where this would be helpful that we can come up with? I’m open to it…
It is useful in cases like letting clients choose server regions.
For ex, some of the clients may want to stick with servers only in EU, or only in California, or only in India. This UDP range trick to pin clients to regions works for those usecases, in particular. Another alternative is to deploy region-specific fly-app per-region…
I’ve mentioned on the forums elsewhere, but I’d also appreciate some form of UDP pinning, that is, connections from the same client ip-port ending up at the same server as packets that arrived before (think connection oriented protocols over UDP, like QUIC, or ones tunneling TCP, like WireGuard).
For both the solutions above, and without having to maintain a map, may be some form of consistent-hashing / rendezvous-hashing client-ip (ignoring the client-port, for now) among VMs in a single region does the trick (but this has other pitfalls like poor load-balancing properties and so could be exposed behind a feature flag)?