Oh wow, that’s sad news (though not entirely surprising). Thanks for explaining; I didn’t see the announcement.
I now see that the page Public Network Services · Fly Docs has already been updated, but there are several other pages that I think should mention this:
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App Configuration (fly.toml) · Fly Docs says “
port: An integer representing the external port to listen on (ports 1-65535).” I think the text below should mention that by default an app’s IPv4 address is shared, so it only supports ports 80 and 443 (running HTTP and TLS+HTTP respectively); other ports and protocols require a dedicated IPv4/IPv6 address. -
I feel like Troubleshooting your Deployment · Fly Docs should also mention the deal with shared IPv4 addresses (and how to check whether the app’s IPv4 address is shared or dedicated).
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Running Fly.io Apps On UDP and TCP · Fly Docs should mention that the demo requires a dedicated IPv4 address. Bonus typo: In the line
echo hello world | nc udp-echo-sample.fly.dev 5000,ncshould be changed tonc -u(otherwise it uses TCP).
I note that people who want to try Fly.io without spending money won’t be able to create UDP services, because (if I understand it correctly) UDP can’t work on a shared IPv4 address, and is not supported over IPv6, so it requires a (paid) dedicated IPv4 address.