kubeadm Cluster Create & Upgrade

Upgrade Order (Must Follow)

• Always upgrade kubeadm first
• Upgrade control plane nodes before worker nodes
• kubelet must be upgraded manually on every node

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Upgrade kubeadm

Check Available Versions

apt-cache show kubeadm

Install Specific kubeadm Version

apt-get install kubeadm=1.34.3-1.1
kubeadm version

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Upgrade the Control Plane

See Upgrade Plan

kubeadm upgrade plan

Apply Upgrade (Example Version)

kubeadm upgrade apply v1.34.1

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Upgrade kubelet and kubectl

apt-get install kubelet=1.34.1-1.1 kubectl=1.34.1-1.1
systemctl restart kubelet

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Create a Cluster (kubeadm init)

Basic Init

kubeadm init --kubernetes-version=1.34.1

Init with Pod Network CIDR

kubeadm init \
  --kubernetes-version=1.34.1 \
  --pod-network-cidr=192.168.0.0/16 \
  --ignore-preflight-errors=NumCPU,Mem

Pod Network CIDR Notes

• Required for some CNIs (Calico, Flannel)
• Must be valid CIDR (0–255 per octet)
• Must not conflict with host or service CIDR

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Configure kubectl Access

mkdir -p /root/.kube
cp /etc/kubernetes/admin.conf /root/.kube/config

If copying to another node:

scp /etc/kubernetes/admin.conf node-summer:/root/.kube/config

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Join Worker Nodes

Generate Join Command

kubeadm token create --print-join-command

Example Join

kubeadm join 172.30.1.2:6443 \
  --token m3qmx4.qa9c83ju82ru6njq \
  --discovery-token-ca-cert-hash sha256:4b0e1b1109e852de2f92bbb4bf0bdeae7616dd94ec1a35da21ba7ba83c0bb441

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