[Kubernetes] Install Kubernetes in Ubuntu Linux

There are different platforms to run Kubernetes (K8S) nowadays. In cloud, we can consider AWS Elastic Kubernetes Service, Azure Kubernetes Service, or we can install Talos in on-premise infrastructure as quick win solution. However, actually we can install K8S in different Linux distributions. This article will step by step on how to install Kubernetes 1.24.3 in Ubuntu 22.04 with 1 master node and 1 worker node. Since 1.22, platform K8S not support docker swarm and switch to containerd since 1.22, so there has a sigh different during installation. That why I wrote this page for recording.

Steps

1. Enable kernal modules for containerd.
   In shell, execute command below.

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

2. Initialize system settings for K8S networking.
   In shell, execute command below.

   sudo 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

3. Prepare applications to use in following steps.
   In shell, execute command below.

   sudo apt update
   sudo apt install -y apt-transport-https curl

4. Disable swap in OS.
   In shell, execute command below.

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

5. Install containerd
   In shell, execute command below.

   sudo apt install -y ca-certificates curl gnupg lsb-release
   curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
   echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list
   sudo apt update
   sudo apt install -y containerd.io

6. Configure containerd
   In shell, execute command below.

   sudo mkdir -p /etc/containerd 
   sudo containerd config default | sudo tee /etc/containerd/config.toml 
   sudo sed -i 's/SystemdCgroup = false/SystemdCgroup = true/' /etc/containerd/config.toml && grep 'SystemdCgroup' -B 11 /etc/containerd/config.toml
   sudo systemctl enable --now containerd
   sudo systemctl restart containerd

7. Install K8S
   In shell, execute command below.

   curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
   cat << EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
   deb https://apt.kubernetes.io/ kubernetes-xenial main
   EOF
   sudo apt update
   sudo apt install -y kubelet=$KUBERNETES_VERSION kubectl=$KUBERNETES_VERSION kubeadm=$KUBERNETES_VERSION
   sudo apt-mark hold kubelet kubeadm kubectl
   sudo systemctl enable --now kubelet

8. [For Master node only] Initialize K8S cluster.
   In shell, execute command below.

   sudo kubeadm init --pod-network-cidr $POD_NETWORK_CIDR --kubernetes-version $KUBERNETES_VERSION

9. [For Master node only] Setup master node local settings.
   In shell, execute command below.

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

10. [For Master node only] Setup Calico.
    In shell, execute command below.

    kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

11. [For Master node only] Generate command for worker nodes joining cluster.
    In shell, execute command below.

    kubeadm token create --print-join-command

    It should be generate command like this, copy it to clipboard.
    

12. [For Worker node only] Join K8S cluster.
    In shell, execute command which copied from previous steps.
    
13. Verify result.
    In master node shell, execute command below

    kubectl get po -A -o wide

    Expected it will show all namespace pods and its deployed pod.
    

Related shell script has been push in GitHub repository.