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## Prerequisites
Minimal Installed Debian 12 /11
2 CPU / vCPU
2 GB RAM
20 GB free disk space
Sudo User with Admin rights
Stable Internet Connectivity
Ensure that each node can communicate with the others via a reliable network connection.
Lab Setup
For the demonstration, I am using three Debian 12 systems.
Master Node (k8s-master) 192.168.1.23
Worker Node 1 (k8s-worker01) 192.168.1.24
Worker Node 2 (k8s-worker02) 192.168.1.25
Without any further delay, lets jump into Kubernetes Cluster installation steps.
## Set Host Name and Update Hosts File
Login to each node (master & woker nodes) and set their hostname using hostnamectl command.
$ sudo hostnamectl set-hostname "k8s-master.linuxtechi.local" // Run on master node
$ sudo hostnamectl set-hostname "k8s-worker01.linuxtechi.local" // Run on 1st worker node
$ sudo hostnamectl set-hostname "k8s-worker02.linuxtechi.local" // Run on 2nd worker node
Also add the following entries in /etc/hosts file on all the nodes,
192.168.1.23 k8s-master.linuxtechi.local k8s-master
192.168.1.24 k8s-worker01.linuxtechi.local k8s-worker01
192.168.1.25 k8s-worker02.linuxtechi.local k8s-worker02
## Disable Swap on All Nodes
For kubelet to work smoothly, it is recommended to disable swap. Run following commands on master and worker nodes to turn off swap.
$ sudo swapoff -a
$ sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab
## Add Firewall Rules for Kubernetes Cluster
In case, OS firewall is enabled on your Debian systems then allow following ports on master and worker nodes respectively.
On Master node, run
$ 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
Note: If firewall is disabled on your Debian 12/11 systems, then you can skip this step.
## Install Containerd Run time on All Nodes
Containerd is the industry standard container run time and supported by Kubernetes. So, install containerd on all master and worker nodes.
Before installing containerd, set the following kernel parameters on all the nodes.
$ 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-k8s.conf
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF
To make above changes into the effect, run
$ sudo sysctl --system
Now, install conatinerd by running following apt command on all the nodes.
$ sudo apt update
$ sudo apt -y install containerd
Next, configure containerd so that it works with Kubernetes, run beneath command on all the nodes
$ containerd config default | sudo tee /etc/containerd/config.toml >/dev/null 2>&1
Set cgroupdriver to systemd on all the nodes,
Edit the file /etc/containerd/config.toml and look for the section [plugins.”io.containerd.grpc.v1.cri”.containerd.runtimes.runc.options] and change SystemdCgroup = false to SystemdCgroup = true
$ sudo vi /etc/containerd/config.toml
Enable-SystemCgroup-Containerd-Debain12
Save and exit the file.
Restart and enable containerd service on all the nodes,
$ sudo systemctl restart containerd
$ sudo systemctl enable containerd
## Add Kubernetes Apt Repository
In Debian 12/11, Kubernetes related packages are not available in the default package repositories. We have to add additional Kubernetes apt repository on all the nodes, run
$ echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.28/deb/ /" | sudo tee /etc/apt/sources.list.d/kubernetes.list
$ curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.28/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
## Install Kubernetes Tools
Next, install the Kubernetes tools, including kubeadm, kubelet, and kubectl on all the nodes.
$ sudo apt update
$ sudo apt install kubelet kubeadm kubectl -y
$ sudo apt-mark hold kubelet kubeadm kubectl
## Install Kubernetes Cluster with Kubeadm
kubelet doesnt appreciate the command-line options anymore (these are deprecated). Instead, I suggest to create a configuration file, say kubelet.yaml with following content.
$ vi kubelet.yaml
apiVersion: kubeadm.k8s.io/v1beta3
kind: InitConfiguration
---
apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
kubernetesVersion: "1.28.0" # Replace with your desired version
controlPlaneEndpoint: "k8s-master"
---
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
Now, we are all set to initialize Kubernetes cluster, run following command only from master node,
$ sudo kubeadm init --config kubelet.yaml
Output,
Install-Kubernetes-Cluster-Debian12-Kubeadm-Output
Above output confirms that control plane has been initialized successfully. In the output, we have commands for regular user for interacting with the cluster and also the command to join any worker node to this cluster.
To start interacting with cluster, run following commands on master node,
$ mkdir -p $HOME/.kube
$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$ sudo chown $(id -u):$(id -g) $HOME/.kube/config
Run following kubectl command to get nodes and cluster information,
$ kubectl get nodes
$ kubectl cluster-info
Output of above commands,
Kubernetes-Cluster-information-Debian12
On your worker nodes, join them to the cluster by running the command that was displayed when you initialized the master node. It will look something like this Kubeadm join
Note: Copy the exact command from the output of kubeadm init command. In my case, following is the command
$ sudo kubeadm join k8s-master:6443 --token 21nm87.x1lgd4jf0lqiiiau \
--discovery-token-ca-cert-hash sha256:28b503f1f2a2592678724c482776f04b445c5f99d76915552f14e68a24b78009
Output from Worker Node 1,
Worker01-Join-Kubernetes-Cluster-Debain12
Output from Worker Nod 2 ,
Worker02-Join-Kubernetes-Cluster-Debain12
Check the nodes status by running following command from master node,
$ kubectl get nodes
Kubectl-Get-Nodes-Debian12
To make nodes status ready, we must install POD network addons like Calico or flannel.
## Setup Pod Network Using Calico
On the master node, run beneath command to install calico,
$ kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.26.1/manifests/calico.yaml
Output,
Install-Calico-Pod-Network-Addon-K8s-Debian12
Allow Calico ports in OS firewall, run beneath ufw commands on all the 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 the status of Calico pods, run
$ kubectl get pods -n kube-system
Calico-Pods-Status-Kubernetes-Debian12
Perfect, now check nodes status again,
Nodes-Status-Post-Calico-Installation-K8s-Debian12
Great, above confirms that master and worker nodes are in ready staate. Now, we can say our cluster ready handle workload.
## Test Kubernetes Cluster Installation
In order validate and test Kubernetes cluster installation, lets try to deploy nginx based application via deployment. Run beneath commands,
$ 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
Output of above commands,
Sample-Nginx-Deployment-Kubernetes-Cluster-Debian12
Try to access the nginx based application using following curl command along with the nodeport 32283.
Note : In the curl command we can use either of worker nodes hostname.
$ curl http://k8s-worker01:32283
Access-Nginx-Deployment-Kubernetes-Cluster-Debian12
Great, output above confirms that we are able to access our nginx based application.
Thats all from this guide, I hope you have found it informative and able to install Kubernetes cluster on Debian 12 smoothly.