Are you looking for an easy guide on how to install Kubernetes Cluster on Ubuntu 22.04 (Jammy Jellyfish)?

The step-by-step guide on this page will show you how to install Kubernetes cluster on Ubuntu 22.04 using Kubeadm command step by step.

Kubernetes is a free and open-source container orchestration tool, it also known as k8s. With the help of Kubernetes, we can achieve automated deployment, scaling and management of containerized application.

A Kubernetes cluster consists of worker nodes on which application workload is deployed and a set up master nodes which are used to manage worker nodes and pods in the cluster.

In this guide, we are using one master node and two worker nodes. Following are system requirements on each node,

• Minimal install Ubuntu 22.04
• Minimum 2GB RAM or more
• Minimum 2 CPU cores / or 2 vCPU
• 20 GB free disk space on /var or more
• Sudo user with admin rights
• Internet connectivity on each node

Lab Setup

• Master Node:  192.168.1.173 – k8smaster.example.net
• First Worker Node:  192.168.1.174 – k8sworker1.example.net
• Second Worker Node:  192.168.1.175 – k8sworker2.example.net

Without any delay, let’s jump into the installation steps of Kubernetes cluster

Step 1) Set hostname and add entries in the hosts file

Login to to master node and set hostname using hostnamectl command,

sudo hostnamectl set-hostname "k8smaster.example.net"

On the worker nodes, run

sudo hostnamectl set-hostname "k8sworker1.example.net"

sudo hostnamectl set-hostname "k8sworker2.example.net"

Add the following entries in /etc/hosts file on each node

192.168.1.173   k8smaster.example.net k8smaster
192.168.1.174   k8sworker1.example.net k8sworker1
192.168.1.175   k8sworker2.example.net k8sworker2

Step 2) Disable swap & add kernel settings

Execute beneath swapoff and sed command to disable swap. Make sure to run the following commands on all the nodes.

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

Load the following kernel modules on all the nodes,

sudo tee /etc/modules-load.d/containerd.conf <<EOF
br_netfilter
EOF
sudo modprobe br_netfilter

Set the following Kernel parameters for Kubernetes, run beneath tee command

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

Reload the above changes, run

sudo sysctl --system

Step 3) Install containerd run time

In this guide, we are using containerd run time for our Kubernetes cluster. So, to install containerd, first install its dependencies.

sudo apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificates

Enable docker repository

sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/docker.gpg
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

Now, run following apt command to install containerd

sudo apt update
sudo apt install -y containerd.io

Configure containerd so that it starts using systemd as cgroup.

containerd config default | sudo tee /etc/containerd/config.toml >/dev/null 2>&1
sudo sed -i 's/SystemdCgroup \= false/SystemdCgroup \= true/g' /etc/containerd/config.toml
sudo sed -i 's/snapshotter \= "overlayfs"/snapshotter \= "zfs"/g' /etc/containerd/config.toml

You will now need to create a zpool to use as the snapshotter for containerd. If you create this in the default path everything should work with the config created above, but you might need to set the path for the zfs snapshotter if you want a different path.

sudo zfs create -o mountpoint=/var/lib/containerd/io.containerd.snapshotter.v1.zfs <your zfs pool>/containerd

Restart and enable containerd service

sudo systemctl restart containerd
sudo systemctl enable containerd

Step 4) Add apt repository for Kubernetes

Execute following commands to add apt repository for Kubernetes

sudo curl -fsSL https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/google.gpg
sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"

Note: At time of writing this guide, Xenial is the latest Kubernetes repository but when repository is available for Ubuntu 22.04 (Jammy Jellyfish) then you need replace xenial word with ‘jammy’ in ‘apt-add-repository’ command.

Step 5) Install Kubernetes components Kubectl, kubeadm & kubelet

Install Kubernetes components like kubectl, kubelet and Kubeadm utility on all the nodes. Run following set of commands,

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

Step 6) Initialize Kubernetes cluster with Kubeadm command

Now, we are all set to initialize Kubernetes cluster. Run the following Kubeadm command from the master node only.

sudo kubeadm init --control-plane-endpoint=k8smaster.example.net

Output of above command should end with something like the following,

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

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

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 10.0.0.42:6443 --token vt4ua6.23wer232423134 \
        --discovery-token-ca-cert-hash sha256:3a2c36feedd14cff3ae835abcdefgesadf235adca0369534e938ccb307ba5

As the output above confirms that control-plane has been initialize successfully. In output also we are getting set of commands for interacting the cluster and also the command for worker node to join the cluster.

So, to start interacting with cluster, run following commands from the 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

Now, try to run following kubectl commands to view cluster and node status

kubectl cluster-info
kubectl get nodes

Output,

user@server:~ $ kubectl cluster-info
Kubernetes control plane is running at https://10.0.0.42:6443
CoreDNS is running at https://10.0.0.42:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
user@server:~ $ kubectl get nodes
NAME         STATUS   ROLES           AGE    VERSION
k8smaster   Ready    control-plane   153m   v1.26.1

If you only want to have one node you can run the following to allow scheduling on the master

kubectl taint node k8smaster node-role.kubernetes.io/master:NoSchedule-
kubectl taint nodes --all node-role.kubernetes.io/master-
kubectl taint nodes --all  node-role.kubernetes.io/control-plane-

Join both the worker nodes to the cluster, command is already there is output, just copy paste on the worker nodes,

sudo kubeadm join k8smaster.example.net:6443 --token vt4ua6.23wer232423134 \
   --discovery-token-ca-cert-hash sha256:3a2c36feedd14cff3ae835abcdefgesadf235adca0369534e938ccb307ba5

Output from both the worker nodes,

Check the nodes status from master node using kubectl command,

kubectl get nodes

As we can see nodes status is ‘NotReady’, so to make it active. We must install CNI (Container Network Interface) or network add-on plugins like Calico, Flannel and Weave-net.

Step 6) Install Calico Pod Network Add-on

Run following curl and kubectl command to install Calico network plugin from the master node,

curl https://projectcalico.docs.tigera.io/manifests/calico.yaml -O
kubectl apply -f calico.yaml

Output of above commands would look like below,

Verify the status of pods in kube-system namespace,

kubectl get pods -n kube-system

Output,

Perfect, check the nodes status as well.

kubectl get nodes

Great, above confirms that nodes are active node. Now, we can say that our Kubernetes cluster is functional.

Step 7) Test Kubernetes Installation

To test Kubernetes installation, let’s try to deploy nginx based application and try to access it.

kubectl create deployment nginx-app --image=nginx --replicas=2

Check the status of nginx-app deployment

kubectl get deployment nginx-app
NAME        READY   UP-TO-DATE   AVAILABLE   AGE
nginx-app   2/2     2            2           68s

Expose the deployment as NodePort,

kubectl expose deployment nginx-app --type=NodePort --port=80
service/nginx-app exposed

Run following commands to view service status

kubectl get svc nginx-app
kubectl describe svc nginx-app

Output of above commands,

Use following command to access nginx based application,

curl http://<woker-node-ip-addres>:31246

curl http://192.168.1.174:31246

Output,

Great, above output confirms that nginx based application is accessible.

That’s all from this guide, I hope you have found this guide useful. Most of this post comes from https://www.linuxtechi.com/install-kubernetes-on-ubuntu-22-04/ with modifications to work with ZFS.