Adding Nodes

This cluster uses kubeadm on AlmaLinux with Kubernetes v1.33.

On Master Node

Generate a join token:

kubeadm token create --print-join-command

Copy the output - it will look like:

kubeadm join 10.0.0.219:6443 --token xxxxxx --discovery-token-ca-cert-hash sha256:xxxxxx

On New Node

Run these commands as root:

# 1. Set hostname
hostnamectl set-hostname node05

# 2. Stop firewall
systemctl stop firewalld
systemctl stop iptables

# 3. Disable SELinux
setenforce 0
sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

# 4. Disable swap
swapoff -a
sed -i '/ swap / s/^/#/' /etc/fstab

# 5. Load kernel modules
modprobe overlay
modprobe br_netfilter

# 6. Configure sysctl
cat <<EOF > /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-iptables  = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
EOF
sysctl --system

# 7. Add k8s repo
cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/v1.33/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/v1.33/rpm/repodata/repomd.xml.key
exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
EOF

# 8. Add Docker CE repo and install containerd
dnf install -y dnf-plugins-core
dnf config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
dnf install -y containerd.io
mkdir -p /etc/containerd
containerd config default > /etc/containerd/config.toml
sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml
systemctl enable --now containerd

# 9. Install k8s components
dnf install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

# 10. Enable kubelet
systemctl enable --now kubelet

# 11. Join cluster (USE TOKEN FROM MASTER)
kubeadm join 10.0.0.219:6443 --token <TOKEN> --discovery-token-ca-cert-hash sha256:<HASH>

On Master Node Again

Approve the new node:

kubectl get nodes
kubectl get csr
kubectl approve node node05

Verify:

kubectl get nodes -o wide