Hi.
I have the following setup
```
frontend public_ssl
bind :::443 v4v6
option tcplog
tcp-request inspect-delay 5s
tcp-request content capture req.ssl_sni len 25
tcp-request content accept if { req.ssl_hello_type 1 }
# https://www.haproxy.com/blog/introduction-to-haproxy-maps/
use_backend
%[req.ssl_sni,lower,map(/usr/local/etc/haproxy/tcp-domain2backend-map.txt)]
default_backend be_sni
backend be_sni
server fe_sni 127.0.0.1:10444 weight 10 send-proxy-v2-ssl-cn
frontend https-in
# terminate ssl
bind 127.0.0.1:10444 accept-proxy ssl strict-sni alpn h2,http/1.1 crt
/usr/local/etc/haproxy-certs
mode http
option forwardfor
option httplog
option http-use-htx
option http-ignore-probes
# https://www.haproxy.com/blog/introduction-to-haproxy-maps/
use_backend
%[req.hdr(host),lower,map(/usr/local/etc/haproxy/http-domain2backend-map.txt)]
#---------------------------------------------------------------------
# backends
#---------------------------------------------------------------------
backend nextcloud-backend
mode http
option http-use-htx
option httpchk GET / HTTP/1.1\r\nHost:\ cloud.Domain.com
server short-cloud 127.0.0.1:81 check
```
I know that the backend can't handle h2.
The log line looks like this.
```
::ffff:Client-IP:4552 [18/May/2019:18:21:33.886] https-in~
nextcloud-backend/short-cloud 0/0/0/53/53 200 691 - - ---- 21/3/0/0/0 0/0 "GET
/ocs/v2.php/apps/notifications/api/v2/notifications HTTP/2.0"
```
What variable can I use for the log to see which protocol is used for the
backend, as with htx the frontend can have different http proto then the
backend?
I haven't seen any variable in the custom log fields which reflects the backend
protocol.
https://cbonte.github.io/haproxy-dconv/1.9/configuration.html#8.2.4
Best regards
Aleks
