check_apiserver.sh

#!/bin/sh

errorExit() {
    echo "*** $*" 1>&2
    exit 1
}

curl --silent --max-time 2 --insecure https://localhost:6443/ -o /dev/null || errorExit "Error GET https://localhost:6443/"
if ip addr | grep -q VIRTUAL_IP; then
    curl --silent --max-time 2 --insecure https://VIRTUAL_IP:6443/ -o /dev/null || errorExit "Error GET https://VIRTUAL_IP:6443/"
fi

haproxy.conf

...
frontend k8s-api
  bind *:5443
  mode tcp
  option tcplog
  default_backend k8s-api

backend k8s-api
  mode tcp
  option tcplog
  option tcp-check
  balance roundrobin
  default-server inter 10s downinter 5s rise 2 fall 2 slowstart 60s maxconn 250 maxqueue 256 weight 100
  server k8s-api-1 192.168.xx.x:6443 check
  server k8s-api-2 192.168.xx.x:6443 check
  server k8s-api-3 192.168.xx.x:6443 check
  server k8s-api-4 192.168.xx.x:6443 check

keepalived.conf

! Configuration File for keepalived
global_defs {
  router_id LVS_DEVEL
}

vrrp_script check_apiserver {
  script "/etc/keepalived/check_apiserver.sh"
  interval 3
  weight -2
  fall 10
  rise 2
}

vrrp_instance VI_1 {
    state MASTER
    interface wlan0
    virtual_router_id 51
    priority 101
    authentication {
        auth_type PASS
        auth_pass mysuperstrongpassword
    }
    virtual_ipaddress {
        192.168.xx.x
    }
    track_script {
        check_apiserver
    }
}

kube cluster

export USER=pi
export SERVER_IP=192.168.x.x
export NEXT_SERVER_IP=192.168.x.x

k3sup install \
  --ip $SERVER_IP \
  --user $USER \
  --k3s-extra-args '--no-deploy traefik' \
  --local-path ~/.kube/config \
  --cluster

k3sup join \
  --ip $NEXT_SERVER_IP \
  --user $USER \
  --server-user $USER \
  --k3s-extra-args '--no-deploy traefik' \
  --server-i