A few days ago I read a good writeup on how much HTTP/3 can shave off page loads — QUIC drops a round trip on connection setup and survives network changes without renegotiating. I wanted it on my own sites.
All of them deploy with Kamal, which fronts each app with kamal-proxy. The good news: kamal-proxy already speaks HTTP/3 — it has an --http3 flag. The bad news: Kamal gave me no way to turn it on.
Two things were missing, and the second is the subtle one:
Kamal never passes --http3 to the proxy.
The proxy container only publishes TCP 80 and 443. HTTP/3 runs over QUIC, which is UDP — so even with the flag set, the UDP 443 listener would sit there unreachable.
