found the solution:
Defining virtual hosts (/etc/hosts).
global
log stdout format raw local0
defaults
log global
mode http
option httplog
timeout client 30s
timeout server 30s
timeout connect 30s
frontend http-in
bind *:80
acl is_openhab hdr_sub(host) -i openhab
use_backend openhab_backend if is_openhab
acl is_grafana hdr_sub(host) -i grafana
use_backend grafana_backend if is_grafana
acl is_nodered hdr_sub(host) -i nodered
use_backend nodered_backend if is_nodered
acl is_sbserver hdr_sub(host) -i sbserver
use_backend sbserver_backend if is_sbserver
acl is_ccu hdr_sub(host) -i ccu
use_backend ccu_backend if is_ccu
acl is_frontail hdr_sub(host) -i frontail
use_backend frontail_backend if is_frontail
backend grafana_backend
server grafana grafana:3000
backend nodered_backend
server node-red node-red:1880
backend openhab_backend
server openhab openhab:8080
backend sbserver_backend
server sb-server sbserver:9000
backend ccu_backend
server ccu homematic-raspi
backend frontail_backend
server frontail frontail:9001