Install Kubernetes on Ubuntu 18.04 LTS
Step1: On All Machines ( Master & All nodes ):
### INSTALL DOCKER 

sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl software-properties-common

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
sudo apt-get update ; clear
sudo apt-get install -y docker-ce

sudo vi /etc/docker/daemon.json

{
	"exec-opts": ["native.cgroupdriver=systemd"]
}

sudo service docker restart


### INSTALL KUBEADM,KUBELET,KUBECTL

echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
sudo apt-get update ; clear
sudo apt-get install -y kubelet kubeadm kubectl	
Step2: On Master only:
sudo kubeadm init --ignore-preflight-errors=all

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

## Weave
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')" 

kubectl get nodes
kubectl get all --all-namespaces
Step3: On Nodes only:
copy the kubeadm join token from master & run it on all nodes
      
Ex: kubeadm join 10.128.15.231:6443 --token mks3y2.v03tyyru0gy12mbt \
       --discovery-token-ca-cert-hash sha256:3de23d42c7002be0893339fbe558ee75e14399e11f22e3f0b34351077b7c4b56
Install Kubernetes on CENTOS
Step1: On All Machines ( Master & All nodes ):
 ### Set SELinux in permissive mode (effectively disabling it)
 
 setenforce 0
 sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

 ### Install Docker
 
 sudo yum remove -y docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine docker-ce docker-ce-cli containerd.io
 sudo yum install -y yum-utils device-mapper-persistent-data lvm2
 sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
 sudo yum install -y docker-ce docker-ce-cli containerd.io
 systemctl enable --now docker
 systemctl start docker

 ### Install kubeadm,kubelet,kubectl
 
 cat <<EOF > /etc/yum.repos.d/kubernetes.repo
 [kubernetes]
 name=Kubernetes
 baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
 enabled=1
 gpgcheck=1
 repo_gpgcheck=1
 gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
 EOF

 yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
 systemctl enable --now kubelet
Step2: On Master only:
sudo kubeadm init --ignore-preflight-errors=all

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

## Weave Pod Network
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')" 

kubectl get nodes
kubectl get all --all-namespaces
Step3: On Nodes only:
copy the kubeadm join token from master & run it on all nodes

Ex: kubeadm join 10.128.15.231:6443 --token mks3y2.v03tyyru0gy12mbt \
       --discovery-token-ca-cert-hash sha256:3de23d42c7002be0893339fbe558ee75e14399e11f22e3f0b34351077b7c4b56
how to find kubeadm join token later
kubeadm token create --print-join-command --ttl=0