### Master Node - reference link:
https://github.com/anishrana2001/Kubernetes/blob/main/Kubernetes%20init/master%20node%20steps
https://github.com/anishrana2001/Kubernetes/blob/main/Kubernetes%20init/script%20for%20workernodes
__________________________
### Disable SELINUX ####

cat /etc/sysconfig/selinux | grep SELINUX=
sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux
cat /etc/sysconfig/selinux | grep SELINUX=
setenforce 0
######################


### Make DNS local entries ### Change it as per your requirement #####
cat <<EOF>>  /etc/hosts

x.x.x.x  master
x.x.x.x  node-1
EOF
######################

### Check the connectivity of your cluster nodes #########
ping -c 2 master
ping -c 2 node-1
######################


### Disable the Firewall ########
systemctl stop firewalld.service
systemctl disable firewalld
systemctl status firewalld
######################

### Kubernetes prerequisite #######
RAM=`cat /proc/meminfo | grep MemTotal | awk '{print ($2 / 1024) / 1024 ,"GiB"}'`
CPU=`cat /proc/cpuinfo | grep processor`

sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab
swapoff -a
echo "Your system RAM is $RAM"
echo "Your system CPU are $CPU"
######################


### Preparation for Docker installation #########
modprobe br_netfilter
lsmod | grep br_netfilter

echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables
sysctl -a | grep net.bridge.bridge-nf-call-iptables
######################


### Docker installation steps #######
sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-engine
sudo yum install -y yum-utils
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
sudo yum install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
containerd config default | sudo tee /etc/containerd/config.toml
sed -i 's/SystemdCgroup = false/SystemdCgroup = true/g' /etc/containerd/config.toml
systemctl start docker
systemctl enable docker
sudo groupadd docker
sudo usermod -aG docker $USER
newgrp docker
# Exit from terminal and re-login and run below command
docker run hello-world
######################


### Kubernetes installation steps #####
cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/v1.28/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/v1.28/rpm/repodata/repomd.xml.key
exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
EOF

yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
systemctl enable kubelet
systemctl start kubelet
#####################

### Create Kubernetes Cluster #####
swapoff -a
kubeadm init 

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

### You should now deploy a Pod network to the cluster. ####
kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.3/manifests/tigera-operator.yaml
kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.3/manifests/custom-resources.yaml
curl https://raw.githubusercontent.com/projectcalico/calico/v3.27.3/manifests/calico.yaml -O
kubectl apply -f calico.yaml
Kubectl apply -f calico.yaml

------------------------------------------------------------

## Use same above steps for installing kubernetes and docker on worker nodes and then run below command to join worker node to master node
(You will get below command after kubeadm init, if you don't have commands then you can run --- sudo kubeadm token create --print-join-command)
kubeadm join 192.168.1.31:6443 --token ********* command need to be add"