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Day 24. Create Kubernetes Cluster

Day 24. Create Kubernetes Cluster

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Ashvini Mahajan
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Table of contents

Prerequisites

Before diving into the installation, ensure that your environment meets the following prerequisites:

  • An Ubuntu 22.04 system.

  • Minimum 2GB RAM or more.

  • Minimum 2 CPU cores (or 2 vCPUs).

  • 20 GB of free disk space on /var (or more).

  • Custom ICMP rule for all nodes in Security Group

  • Ensure machines in the cluster can ping each other via IP and hostname.

  • 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 upgrade

  • 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/fstab

  • 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_netfilter
  • Configure 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
EOF
  • Then, reload the changes:
sudo sysctl --system

  • Install Containerd Runtime (all nodes)

    We are using the containerd runtime. Install containerd and its dependencies with the following commands:

sudo apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificates
  • Enable the 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"
  • Update the package list and install containerd:
sudo apt update
sudo apt install -y containerd.io
  • Configure containerd to start 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
  • Restart and enable the containerd service:
sudo systemctl restart containerd
sudo systemctl enable containerd

  • 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:

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:/v1.29/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
sudo apt update

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

  • 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 init

  • After 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/config
  • Next, use kubectl commands to check the cluster and node status:
kubectl get nodes

  • Add Worker Nodes to the Cluster (worker nodes)

    On each worker node, use the kubeadm join command you noted down earlier:

    Open port 6443 on all nodes

kubeadm join 172.31.26.104:6443 --token lit28c.xikm96pa63xb1c0k \
        --discovery-token-ca-cert-hash sha256:ef3b21607fc490f882e74366d16780de35bc0b3446af82e5a02f8a0e5bb712f4

  • list all nodes on master-node
kubectl get nodes

  • 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.yaml

  • Verify the cluster and test (master node)

    Finally, we want to verify whether our cluster is successfully created.

kubectl get pods -n kube-system
kubectl get nodes

  • Deploy test application on cluster (master node)
kubectl run nginx --image=nginx

#kubernetes cluster