Kubernetes Installation on Rhel/Centos8

Kubernetes Cluster Installation:

Step1: Update hostname

#sudo hostnamectl set-hostname master-node # Change as needed per node

Update (/etc/hosts) on all nodes:

192.168.1.202 master-node

192.168.1.203 worker-node1

192.168.1.204 worker-node2

Step2: Stop firewall

#systemctl stop firewalld

#systemcttl disable firewalld

Step3: Stop swap

#sudo swapoff -a

#sudo sed -i '/swap/d' /etc/fstab

Step4: Disable selinux

#sudo setenforce 0

#sudo sed -i 's/^SELINUX=enforcing/SELINUX=disabled/'/etc/selinux/config

Then Reboot the server

after reboot check the selinux status its disable or not

#getenforce

Step5: Configure Kernel Modules and sysctl

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf

overlay

br_netfilter

EOF

sudo modprobe overlay

sudo modprobe br_netfilter

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf

net.bridge.bridge-nf-call-ip6tables = 1

net.bridge.bridge-nf-call-iptables = 1

net.ipv4.ip_forward = 1

EOF

sudo sysctl --system

step6: Install and Configure Container Runtime (containerd)

sudo dnf install -y containerd

sudo mkdir -p /etc/containerd

containerd config default | sudo tee /etc/containerd/config.toml

Change cgroup driver to systemd:

sudo sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml

sudo systemctl restart containerd

sudo systemctl enable containerd

Step7:Now Installation kubernetes

Create a kubernetes repo

#vi /etc/yum.repos.d/kubernetes.repo

[kubernetes]

name=Kubernetes

baseurl=https://pkgs.k8s.io/core:/stable:/v1.31/rpm/

enabled=1

gpgcheck=1

gpgkey=https://pkgs.k8s.io/core:/stable:/v1.31/rpm/repodata/repomd.xml.key

exclude=kubelet kubeadm kubectl

#dnf update -y

Now installa kubernetes packages

dnf install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

Now start the service

sudo dnf install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

sudo systemctl enable --now kubelet

Initialize Kubernetes Cluster (Master Only)

sudo kubeadm init --pod-network-cidr=192.168.0.0/16

Set up kubectl access:

mkdir -p $HOME/.kube

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

sudo chown $(id -u):$(id -g) $HOME/.kube/config

Install Calico CNI (or another CNI)

curl https://raw.githubusercontent.com/projectcalico/calico/v3.26.1/manifests/custom-resources.yaml -O

kubectl create -f custom-resources.yaml

Join Worker Nodes

Run the command copied from the kubeadm init output:

sudo kubeadm join 192.168.56.10:6443 --token abcdef.0123456789abcdef \

--discovery-token-ca-cert-hash sha256:xxxxxxxxxxxxxxxxxxxxxxxxxxxx

Verify Cluster Status:

kubectl get nodes

kubectl get pods -A

Troubleshoot:

sudo kubeadm reset -f

sudo rm -rf /etc/cni /var/lib/cni /var/lib/kubelet /etc/kubernetes /var/lib/etcd

sudo systemctl restart containerd

$ kubeadm token create --print-join-command