Install Kubernetes on CentOS 7 / Redhat 7

Before starting make sure you configured permanent hostnames for the master and worker nodes this can be done editing /etc/hosts file or using command :

hostnamectl set-hostname master

and on the worker node

hostnamectl set-hostname workder1

Configure Kubernetes Repository - packages not available in the official Repos

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

Run installation commands

sudo yum install -y kubelet kubeadm kubectl

Enable and Start Service

systemctl enable kubelet
systemctl start kubelet

if firewald is running enable the following ports

sudo firewall-cmd --permanent --add-port=6443/tcp
sudo firewall-cmd --permanent --add-port=2379-2380/tcp
sudo firewall-cmd --permanent --add-port=10250/tcp
sudo firewall-cmd --permanent --add-port=10251/tcp
sudo firewall-cmd --permanent --add-port=10252/tcp
sudo firewall-cmd --permanent --add-port=10255/tcp
sudo firewall-cmd --reload

and for the worker nodes

sudo firewall-cmd --permanent --add-port=10251/tcp
sudo firewall-cmd --permanent --add-port=10255/tcp
firewall-cmd --reload

Disable selinux

sudo setenforce 0
sudo sed -i ‘s/^SELINUX=enforcing$/SELINUX=disabled/’ /etc/selinux/config

disable swap

sudo sed -i '/swap/d' /etc/fstab
sudo swapoff -a

Initialize the kubernetes cluster

sudo kubeadm init

enable your user to administer the cluster

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

Join Worker node to the cluster ( the exact command will be printed once you finish creating the cluster)

kubeadm join 10.0.0.47:6443 –token f08041.ns5XXXXXXXXXXXXXXX \
–discovery-token-ca-cert-hash sha256:3d3e27XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX688d

Check Status of the kubernetes installation

Nodes Status

sudo kubectl get nodes

Pods Status

sudo kubectl get pods --all-namespaces

Start / Restart script for Kubernetes 1.24 on CentOS

#!/bin/sh

containerd config default | tee /etc/containerd/config.toml
sed -i ‘s/SystemdCgroup = false/SystemdCgroup = true/g’ /etc/containerd/config.toml
service containerd restart
systemctl restart docker
service kubelet restart

Attachment: start_k8s.sh_.txt