🐳 Bootstrapping a Kubernetes Cluster with kubeadm

Kubernetes has become the de facto standard for container orchestration, providing scalability, resilience, and automation for modern applications. While there are multiple ways to set up a Kubernetes cluster—such as managed services (EKS, AKS, GKE) or tools like kOps—kubeadm remains one of the most direct and flexible methods for bootstrapping a production-grade or lab environment cluster.

In this article, we’ll walk through what kubeadm is, why you might use it, and the steps required to bootstrap your own Kubernetes cluster.

✅ What is kubeadm?

kubeadm is a tool provided by the Kubernetes community to simplify the process of creating and managing clusters. It handles the complex, low-level details such as generating certificates, creating configuration files, and starting control plane components.

With kubeadm, you can:

It does not provision infrastructure (like servers or VMs) or handle add-ons (like monitoring), but it provides a clean foundation on which you can build.

✅ Prerequisites

Before you bootstrap a cluster with kubeadm, you’ll need:

Machines: At least two Linux machines (1 control plane + 1 worker). These can be physical, virtual, or cloud instances.
OS: Ubuntu, Debian, CentOS, or another Linux distribution supported by Kubernetes.
Requirements:
- 2 GB RAM (minimum per machine).
- 2 CPUs (recommended).
- Network connectivity between all nodes.
Installed tools:
- containerd or CRI-O as container runtime.
- kubeadm, kubelet, and kubectl.
- Swap disabled (swapoff -a).

✅Step 1: Install Dependencies

				
					# Update packages
sudo apt-get update && sudo apt-get install -y apt-transport-https curl

# Install container runtime (example: containerd)
sudo apt-get install -y containerd

# Add Kubernetes repository
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF

# Install kubeadm, kubelet, kubectl
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl

# Prevent them from being automatically updated
sudo apt-mark hold kubelet kubeadm kubectl

✅Step 2: Initialize the Control Plane

On the master node, initialize the Kubernetes control plane with:

				
					sudo kubeadm init --pod-network-cidr=10.244.0.0/16

Then, set up kubeconfig for your user:

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

✅ Step 3: Install a Pod Network Add-on

Kubernetes needs a networking solution so pods across nodes can talk to each other. For Flannel, run:

				
					kubectl apply -f https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml

You can also use other CNI plugins like Calico or Weave Net depending on your setup.

✅ Step 4: Join Worker Nodes

On each worker node, run the kubeadm join command you saved earlier (from kubeadm init). It looks something like this:

				
					sudo kubeadm join <MASTER_IP>:6443 --token <TOKEN> \
    --discovery-token-ca-cert-hash sha256:<HASH>

This securely connects worker nodes to the control plane.

✅ Step 5: Verify the Cluster

Back on the master node, check the status of nodes and pods:

				
					kubectl get nodes
kubectl get pods -n kube-system

You can also use other CNI plugins like Calico or Weave Net depending on your setup.

🎯 Conclusion

You’ve successfully bootstrapped a Kubernetes cluster using kubeadm. 🎉

This forms the foundation of a production-ready cluster. From here, you can:

Gcp Kubernetes Management

Kubeadm Hosted Management