Setting Up a Multi-Node Kubernetes 1.29 Cluster with Kubeadm: A Step-by-Step Guide#

Prerequisites#

• 3 Virtual Machines (1 for master, 2 for workers)
• Ubuntu 20.04 or later on all VMs
• Root or sudo access on all machines

Step 1: Prepare All Nodes#

Run these steps on all three nodes:

1. Disable swap:

   1
   swapoff -a
   2
   sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab
   

2. Load necessary kernel modules:

   1
   cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
   2
   overlay
   3
   br_netfilter
   4
   EOF
   5
   
   6
   sudo modprobe overlay
   7
   sudo modprobe br_netfilter
   

3. Configure sysctl params:

   1
   cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
   2
   net.bridge.bridge-nf-call-iptables  = 1
   3
   net.bridge.bridge-nf-call-ip6tables = 1
   4
   net.ipv4.ip_forward                 = 1
   5
   EOF
   6
   
   7
   sudo sysctl --system
   

4. Install containerd as the container runtime:

   1
   # Install containerd
   2
   sudo apt-get update && sudo apt-get install -y containerd
   3
   
   4
   # Configure containerd
   5
   sudo mkdir -p /etc/containerd
   6
   containerd config default | sudo tee /etc/containerd/config.toml
   7
   sudo systemctl restart containerd
   

5. Install kubeadm, kubelet, and kubectl:

   1
   sudo apt-get update
   2
   sudo apt-get install -y apt-transport-https ca-certificates curl
   3
   curl -fsSL https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-archive-keyring.gpg
   4
   echo "deb [signed-by=/etc/apt/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
   5
   sudo apt-get update
   6
   sudo apt-get install -y kubelet=1.29.0-00 kubeadm=1.29.0-00 kubectl=1.29.0-00
   7
   sudo apt-mark hold kubelet kubeadm kubectl
   

Step 2: Initialize the Master Node#

On the master node only:

1. Initialize the cluster:

   1
   sudo kubeadm init --pod-network-cidr=192.168.0.0/16 --kubernetes-version=1.29.0
   

2. Set up kubeconfig:

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   mkdir -p $HOME/.kube
   2
   sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
   3
   sudo chown $(id -u):$(id -g) $HOME/.kube/config
   

3. Install Calico network add-on:

   1
   kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml
   

Step 3: Join Worker Nodes#

On each worker node:

1. Run the join command output by kubeadm init on the master node:

   1
   sudo kubeadm join <master-ip>:6443 --token <token> --discovery-token-ca-cert-hash <hash>
   

Step 4: Verify Cluster Status#

On the master node:

1. Check node status:

   1
   kubectl get nodes
   

2. Verify all pods are running:

   1
   kubectl get pods --all-namespaces
   

Key Takeaways#

1. Proper preparation of all nodes is crucial for a successful Kubernetes setup.
2. Kubeadm simplifies the process of bootstrapping a Kubernetes cluster.
3. Calico provides the necessary networking for pod-to-pod communication.
4. Verifying the cluster status is an important final step to ensure everything is working correctly.

Setting up a multi-node Kubernetes cluster manually provides valuable insights into the components and processes involved in cluster initialization and management. This knowledge is invaluable for troubleshooting and maintaining production Kubernetes environments.

This blog post template covers the main steps of setting up a multi-node Kubernetes cluster using kubeadm, as described in your task. It provides a step-by-step guide that readers can follow to replicate the setup. The content is structured to be informative and practical, suitable for a technical audience familiar with basic Linux and virtualization concepts.