haproxy.cfg errors in configuration file. Help needed

Trying to follow these indications:

https://github.com/kubernetes/kubeadm/blob/main/docs/ha-considerations.md#haproxy-configuration

and these indications:

HAProxy use urls in server config?

I'm trying to correctly and properly define haproxy.cfg, but I'm getting errors

This is the content of /run/systemd/resolve/resolv.conf :

root@k8s-eu-1-control-plane-node-1:~# sudo cat /run/systemd/resolve/resolv.conf
# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver kkk.kk.kkk.kk
nameserver qqq.qq.qqq.qq
search invalid

This is the port range:

root@k8s-eu-1-control-plane-node-1:~# cat /proc/sys/net/ipv4/ip_local_port_range
32768   60999

So, I tried to set haproxy.cfg as follows: /etc/haproxy/haproxy.cfg
# https://github.com/kubernetes/kubeadm/blob/main/docs/ha-considerations.md#haproxy-configuration

# /etc/haproxy/haproxy.cfg
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
    #log /dev/log local0
    #log /dev/log local1 notice

    #log /var/log local0
    #log /var/log local1 notice

    daemon

#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 1
    timeout http-request    10s
    timeout queue           20s
    timeout connect         5s
    timeout client          20s
    timeout server          20s
    timeout http-keep-alive 10s
    timeout check           10s

#---------------------------------------------------------------------
# apiserver frontend which proxys to the control plane nodes
#---------------------------------------------------------------------

# https://www.digitalocean.com/community/tutorials/haproxy-network-error-cannot-bind-socket

frontend apiserver
    bind *:45000
    mode tcp
    option tcplog
    default_backend apiserverbackend


resolvers mydns
    nameserver dns1 161.97.189.51:53
    nameserver dns2 161.97.189.52:53
    parse-resolv-conf
    resolve_retries       3
    timeout resolve       1s
    timeout retry         1s
    hold other           30s
    hold refused         30s
    hold nx              30s
    hold timeout         30s
    hold valid           10s
    hold obsolete        30s


#---------------------------------------------------------------------
# round robin balancing for apiserver
#---------------------------------------------------------------------
backend apiserverbackend
    option httpchk GET /healthz
    http-check expect status 200
    mode tcp
    option ssl-hello-chk

    balance     roundrobin
        #server ${HOST1_ID} ${HOST1_ADDRESS}:${APISERVER_SRC_PORT} check

        server k8s-eu-1-control-plane-node-1:6443 resolvers mydns resolve-prefer ipv4

But it returns the error unknown keyword 'mydns':

root@k8s-eu-1-control-plane-node-1:~# sudo haproxy -c -f /etc/haproxy/haproxy.cfg 
[NOTICE]   (39412) : haproxy version is 2.6.15-1ppa1~jammy
[NOTICE]   (39412) : path to executable is /usr/sbin/haproxy
[ALERT]    (39412) : config : [/etc/haproxy/haproxy.cfg:92] : 'server apiserverbackend/k8s-eu-1-control-plane-node-1:6443' : unknown keyword 'mydns'.
[ALERT]    (39412) : config : Error(s) found in configuration file : /etc/haproxy/haproxy.cfg
[ALERT]    (39412) : config : Fatal errors found in configuration.