From heyhgl at gmail.com  Mon Sep  1 02:30:48 2025
From: heyhgl at gmail.com (Glen Huang)
Date: Mon, 1 Sep 2025 10:30:48 +0800
Subject: Possible to make preread work for QUIC?
Message-ID: <CALNXhk1sRs9pw6CEhtLmE0FXg6oB55cT2JW4=G0u51xJz6NMig@mail.gmail.com>

Hi,

I'm experimenting load balancing for a bunch of upstream QUIC servers.
I wonder if nginx is the right tool for this?

I tried a configuration like this, but when doing curl --http3-only
quic2.com, nginx seemed to always send the traffic to the default
upstream [::1]:444.

pid /run/nginx/nginx.pid;
error_log stderr;
daemon off;
events {}
stream {
 map $ssl_preread_server_name $upstream {
  default [::1]:444;
  quic1.com unix:/run/nginx/quic1.sock;
  quic2.com unix:/run/nginx/quic2.sock;
 }
 server {
  listen 443 reuseport;
  listen [::]:443 reuseport;
  ssl_preread on;
  proxy_pass $upstream;
 }
 server {
  listen 443 udp reuseport;
  listen [::]:443 udp reuseport;
  ssl_preread on;
  proxy_pass $upstream;
 }
}

Is my configuration incorrect? Does preread support QUIC? Thanks in advance.