prerequisites

disable swap

MUST disable swap if the kubelet is not properly configured to use swap

sudo swapoff -a

enable IPv4 packet forwarding

#sysctl params required by setup, params persist across reboots
cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.ipv4.ip_forward = 1
EOF
# Apply sysctl params without reboot
sudo sysctl --system

verify MAC address and product_uuid are unique for every node

It might not be unique in virtual machines and produce error

# MAC addr
ip link or ifconfig -a
# product_uuid
sudo cat /sys/class/dmi/id/product_uuid

check required ports

# TCP Inbound 6443 Kubernetes API server All
# TCP Inbound 2379-2380 etcd server client API kube-apiserver, etcd
# TCP Inbound 10250 Kubelet API Self, Control plane
# TCP Inbound 10259 kube-scheduler Self
# TCP Inbound 10257 kube-controller-manager Self
nc 127.0.0.1 6443 -v

making kubectl work

as non-root user

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

as root user

export KUBECONFIG=/etc/kubernetes/admin.conf