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How to Install Kubernetes Cluster on Debian

Published on August 2, 2024

Last updated on August 7, 2024

Setting up a Kubernetes cluster on Debian 12 involves multiple steps, from configuring hostnames to installing necessary tools. Below is a comprehensive guide to help you get started.

Prerequisites

  • Three Debian 12 machines with the following IP addresses:
  • Control Node (k8s-control) – 10.0.0.1
  • Worker Node 1 (k8s-compute01) – 10.0.0.2
  • Worker Node 2 (k8s-compute02) – 10.0.0.3

Step 1: Set Hostnames and Update Hosts File

Login to each node and set their hostname using the hostnamectl command:

sudo hostnamectl set-hostname "k8s-control.mycluster.local"      # Run on control node
sudo hostnamectl set-hostname "k8s-compute01.mycluster.local"    # Run on 1st worker node
sudo hostnamectl set-hostname "k8s-compute02.mycluster.local"    # Run on 2nd worker node

Add the following entries to the /etc/hosts file on all the nodes:

10.0.0.1   k8s-control.mycluster.local     k8s-control
10.0.0.2   k8s-compute01.mycluster.local   k8s-compute01
10.0.0.3   k8s-compute02.mycluster.local   k8s-compute02

Step 1.1: Update system on All Nodes

apt update && apt upgrade -y

Step 2: Disable Swap on All Nodes

To ensure kubelet functions properly, disable swap:

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

Step 3: Configure Firewall Rules for Kubernetes

If your Debian systems have the firewall enabled, open the necessary ports.

On Control Node:

sudo ufw allow 6443/tcp
sudo ufw allow 2379/tcp
sudo ufw allow 2380/tcp
sudo ufw allow 10250/tcp
sudo ufw allow 10251/tcp
sudo ufw allow 10252/tcp
sudo ufw allow 10255/tcp
sudo ufw reload

On Worker Nodes:

sudo ufw allow 10250/tcp
sudo ufw allow 30000:32767/tcp
sudo ufw reload

Step 4: Install Containerd on All Nodes

Containerd is a standard container runtime supported by Kubernetes.

Configure Kernel Parameters:

cat <<EOF | sudo tee /etc/modules-load.d/containerd.conf 
overlay 
br_netfilter
EOF

sudo modprobe overlay 
sudo modprobe br_netfilter

cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1 
net.bridge.bridge-nf-call-ip6tables = 1 
EOF

sudo sysctl --system

Install and Configure Containerd:

sudo apt update
sudo apt -y install containerd

containerd config default | sudo tee /etc/containerd/config.toml >/dev/null 2>&1

sudo sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml

sudo systemctl restart containerd
sudo systemctl enable containerd

Step 5: Add Kubernetes Package Repository

Add the Kubernetes repository to your Debian systems:

sudo mkdir -p /etc/apt/keyrings

echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /" | sudo tee /etc/apt/sources.list.d/kubernetes.list

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg

Step 6: Install Kubernetes Tools

Install kubeadm, kubelet, and kubectl on all nodes:

sudo apt update
sudo apt install kubelet kubeadm kubectl -y
sudo apt-mark hold kubelet kubeadm kubectl

Step 7: Set Up the Kubernetes Cluster with Kubeadm

Create a kubelet configuration file:

cat <<EOF | sudo tee kubelet.yaml
apiVersion: kubeadm.k8s.io/v1beta3
kind: InitConfiguration
---
apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
kubernetesVersion: "1.30.0"  # Replace with your desired version
---
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
EOF

Initialize the Kubernetes cluster on the control node:

sudo kubeadm init --config kubelet.yaml

Set up kubectl on the control node:

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

Verify the cluster:

kubectl get nodes
kubectl cluster-info

Join worker nodes to the cluster using the command displayed during kubeadm init. Example:

sudo kubeadm join k8s-control:6443 --token <token> \
--discovery-token-ca-cert-hash <hash>

Step 8: Install Calico Network Plugin

On the control node, install Calico:

kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.26.1/manifests/calico.yaml

Allow Calico ports in the firewall on all nodes:

sudo ufw allow 179/tcp
sudo ufw allow 4789/udp
sudo ufw allow 51820/udp
sudo ufw allow 51821/udp
sudo ufw reload

Verify Calico pods status:

kubectl get pods -n kube-system

Step 9: Test the Kubernetes Cluster

Deploy a sample Nginx application to verify the cluster:

kubectl create deployment nginx-app --image=nginx --replicas 2
kubectl expose deployment nginx-app --name=nginx-web-svc --type NodePort --port 80 --target-port 80
kubectl describe svc nginx-web-svc

By following these steps, you should have a fully functional Kubernetes cluster running on Debian 12. Enjoy managing your new cluster!

**You might face warnings from crictl like these below:

crictl images WARN[0000] image connect using default endpoints: [unix:///run/containerd/containerd.sock unix:///run/crio/crio.sock unix:///var/run/cri-dockerd.sock]. As the default settings are now deprecated, you should set the endpoint instead.

To fix this, just update crictl config with:

crictl config --set runtime-endpoint=unix:///run/containerd/containerd.sock
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