Kubernetes is a robust container orchestration platform that automates the deployment, scaling, and management of containerized applications. In this post, we will lead you through the steps to install Kubernetes on Ubuntu 22.04. This cluster configuration contains both a master node and worker nodes, allowing you to take full advantage of Kubernetes.
Kubernetes Nodes
In a Kubernetes cluster, you will encounter two distinct categories of nodes:
Master Nodes: These nodes play a crucial role in managing the control API calls for various components within the Kubernetes cluster. This includes overseeing pods, replication controllers, services, nodes, and more.
Worker Nodes: Worker nodes are responsible for providing runtime environments for containers. It’s worth noting that a group of container pods can extend across multiple worker nodes, ensuring optimal resource allocation and management.
Prerequisites
Before diving into the installation, ensure that your environment meets the following prerequisites:
- An Ubuntu 22.04 system.
- Privileged access to the system (root or sudo user).
- Active internet connection.
- Minimum 2GB RAM or more.
- Minimum: 2 CPU cores (or 2 vCPUs).
- 20 GB of free disk space on /var (or more).
Step 1: Update and Upgrade Ubuntu (all nodes)
Begin by ensuring that your system is up-to-date. Open a terminal and execute the following commands:
sudo apt update
sudo apt upgradeStep 2: Disable Swap (all nodes)
To enhance Kubernetes performance, disable swap and set essential kernel parameters. Run the following commands on all nodes to disable all swaps:
sudo swapoff -a
sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstabStep 3: Add Kernel Parameters (all nodes)
Load the required kernel modules on all nodes:
sudo tee /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF
sudo modprobe overlay
sudo modprobe br_netfilterConfigure the critical kernel parameters for Kubernetes using the following:
sudo tee /etc/sysctl.d/kubernetes.conf <<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOFThen, reload the changes:
sudo sysctl --systemStep 4: Install Containerized Runtime (all nodes)
We are using the container runtime. Install containerd and its dependencies with the following commands:
sudo apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificatesInstall docker:
# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc
# Add the repository to Apt sources:
echo \
"deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
$(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
Update the package list and install containerd:
sudo apt update
sudo apt install -y containerd.ioConfigure containerd to start using systemd as a 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.tomlRestart and enable the container service:
sudo systemctl restart containerd
sudo systemctl enable containerdStep 5: Add Apt Repository for Kubernetes (all nodes)
Kubernetes packages are not available in the default Ubuntu 22.04 repositories. Add the Kubernetes repositories with the following commands:
sudo apt-get update
# apt-transport-https may be a dummy package; if so, you can skip that package
sudo apt-get install -y apt-transport-https ca-certificates curl gpg
# If the directory `/etc/apt/keyrings` does not exist, it should be created before the curl command, read the note below.
# sudo mkdir -p -m 755 /etc/apt/keyrings
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.29/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpgStep 6: Install Kubectl, Kubeadm, and Kubelet (all nodes)
After adding the repositories, install essential Kubernetes components, including kubectl, kubelet, and kubeadm, on all nodes with the following commands:
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl
sudo systemctl enable --now kubeletStep 7: Initialize Kubernetes Cluster with Kubeadm (master node)
With all the prerequisites in place, initialize the Kubernetes cluster on the master node using the following Kubeadm command:
sudo kubeadm initAfter the initialization is complete, make a note of the kubeadm join command for future reference.
Run the following commands on 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/configNext, use kubectl commands to check the cluster and node status:
kubectl get nodesStep 8: Add Worker Nodes to the Cluster (worker nodes)
On each worker node, use the kubeadm join command you noted down earlier:
kubeadm join YOURIP:6443 --token YOURTOKEN --discovery-token-ca-cert-hash YOURHASH
Step :9 Install Kubernetes Network Plugin (master node)
To enable communication between pods in the cluster, you need a network plugin. Install the Calico network plugin with the following command from the master node:
kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.25.0/manifests/calico.yamlStep 10: Verify the cluster and test the master node.
Finally, we want to verify whether our cluster is successfully created.
kubectl get pods -n kube-system
kubectl get nodesStep 11: Deploy test application on cluster (master node)
kubectl run nginx --image=nginx