Step-by-step guide to install Kubernetes (K8s) on Red Hat Enterprise Linux (RHEL) 9.5

Here’s a step-by-step guide to install Kubernetes (K8s) on Red Hat Enterprise Linux (RHEL) 9.5, using kubeadm, the official Kubernetes tool.

✅ Prerequisites

Root / sudo access
Swap disabled
Docker or containerd installed
Firewall open for Kubernetes ports
Unique hostname, static IP, and DNS resolution for each node

🔧 Step 1: Disable Swap

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

🔧 Step 2: Set Hostname

sudo hostnamectl set-hostname <node-name>

Example:

sudo hostnamectl set-hostname master-node

🔧 Step 3: Add Kubernetes Repository

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/v1.30/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/v1.30/rpm/repodata/repomd.xml.key
EOF

You can change v1.30 to a specific version if required.

🔧 Step 4: Install kubeadm, kubelet, kubectl

sudo dnf install -y kubelet kubeadm kubectl

Lock their version to avoid accidental upgrades:

sudo dnf mark install kubelet kubeadm kubectl

🔧 Step 5: Enable and Start kubelet

sudo systemctl enable --now kubelet

🔧 Step 6: Install Container Runtime (Containerd)

Kubernetes no longer supports Docker directly; use containerd.

sudo dnf install -y containerd

Generate default config:

sudo mkdir -p /etc/containerd
containerd config default | sudo tee /etc/containerd/config.toml

Enable Systemd cgroup driver:
Edit /etc/containerd/config.toml and set:

[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
  SystemdCgroup = true

Then restart containerd:

sudo systemctl restart containerd
sudo systemctl enable containerd

🔧 Step 7: Enable Kernel Modules and Set 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-iptables = 1
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

sudo sysctl --system

🟩 Step 8: Initialize Kubernetes Cluster (on Master Node)

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

After success, copy the admin config:

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

🟩 Step 9: Install Pod Network Add-on (like Calico or Flannel)

Example with Calico:

kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.0/manifests/calico.yaml

🟨 Step 10: Join Worker Nodes (optional)

On master, you'll get a kubeadm join command—copy that and run it on each worker node.

✅ Verify

kubectl get nodes

You should see your master node in Ready state.

⚠️ Notes

Make sure firewall ports (6443, 10250, etc.) are open.
If using RHEL with SELinux, ensure it's not interfering.
Run kubeadm reset if you need to clean and reinstall.