Introduction
Kubeadm is a powerful tool that simplifies Kubernetes cluster setup. It is designed to provide best-practice defaults while ensuring a secure and production-ready environment. In this guide, we will walk through setting up a Kubernetes cluster using Kubeadm, address common pitfalls, and provide next steps for deploying workloads.
Prerequisites
Before you begin, ensure that you have:
- At least two Linux machines (one master, one or more nodes) running Ubuntu 22.04 or CentOS 8.
- A minimum of 2 CPUs, 2GB RAM per node, and 20GB disk space.
- A non-root user with sudo privileges.
- Container runtime (Docker, containerd, or CRI-O).
- Network connectivity between nodes.
- Disabled swap:
sudo swapoff -a.
Installation Steps
Step 1: Install Dependencies
On all nodes, install required packages:
sudo apt update && sudo apt install -y apt-transport-https curl
curl -fsSL https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
echo "deb https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt update
sudo apt install -y kubelet kubeadm kubectl
sudo systemctl enable kubelet && sudo systemctl start kubelet
Step 2: Initialize the Control Plane (Master Node)
sudo kubeadm init --pod-network-cidr=192.168.0.0/16
After initialization, set up kubectl for the non-root 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: Deploy a Pod Network
Choose a networking solution such as Calico or Flannel. For example, to install Calico:
kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml
Step 4: Join Worker Nodes
Retrieve the join command from the master:
kubeadm token create --print-join-command
Run the output command on each worker node.
Step 5: Verify the Cluster
Check the nodes and pods:
kubectl get nodes
kubectl get pods --all-namespaces
Common Pitfalls & Fixes
| Issue | Solution |
|---|---|
kubeadm init fails due to swap enabled |
Run sudo swapoff -a and remove swap entries from /etc/fstab. |
Worker nodes show NotReady status |
Ensure the network plugin is installed and kube-proxy is running. |
kubectl commands fail |
Check if the KUBECONFIG environment variable is set correctly. |
Next Steps
- Deploy a sample application: Kubernetes Deployment Guide
- Learn about RBAC and security best practices.
- Set up monitoring using Prometheus and Grafana.
By following this guide, you should now have a functional Kubernetes cluster using Kubeadm. 🚀
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