ngx_stream_ssl_preread_module

https://docshome.gitbook.io/nginx-docs/he-xin-gong-neng/stream/ngx_stream_ssl_preread_module

允许从clienthello中提取信息，而不会终止SSL/TLS,例如通过sni请求的服务器名称

map $ssl_preread_server_name $name {
    backend.example.com      backend;
    default                  backend2;
}

upstream backend {
    server 192.168.0.1:12345;
    server 192.168.0.2:12345;
}

upstream backend2 {
    server 192.168.0.3:12345;
    server 192.168.0.4:12345;
}

server {
    listen      12346;
    proxy_pass  $name;
    ssl_preread on;
}