Installing Kubernetes using Kubeadm on Ubuntu: A Step-by-Step Guide

Introduction

Kubernetes has emerged as the go-to solution for container orchestration and management. If you’re looking to set up a Kubernetes cluster on a Ubuntu server, you’re in the right place. In this step-by-step guide, we’ll walk you through the process of installing Kubernetes using Kubeadm on Ubuntu.

Prerequisites

I have created 3 VMs for Kubernetes Cluster Nodes to Cloud Google Compute Engine (GCE)

• Master(1): 2 vCPUs – 4GB Ram
• Worker(2): 2 vCPUs – 2GB RAM
• OS: Ubuntu 16.04 or CentOS/RHEL 7

I have configured Firewall Rules Ingress in Google Compute Engine (GCE)

• Master Node: 2379,6443,10250,10251,10252
• Worker Node: 10250,30000-32767

Installing Kubernetes using Kubeadm on Ubuntu

Set hostname on Each Node

# hostnamectl set-hostname "k8s-master"    // For Master node
# hostnamectl set-hostname "k8s-worker1"   // For 1st worker node
# hostnamectl set-hostname "k8s-worker2"   // For 2nd worker node

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

192.168.1.14   k8s-master
192.168.1.16   k8s-worker1
192.168.1.17   k8s-worker2

Disable Swap and Bridge Traffic

Kubernetes does not work well with swap enabled. Run it on MASTER & WORKER Nodes

Disable SWAP

# swapoff -a
# sed -i.bak -r 's/(.+ swap .+)/#\1/' /etc/fstab

Load the following kernel modules on all the nodes,

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

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

# 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

# sysctl --system

For example, The output terminal of worker1.

Installing Docker

Run it on MASTER & WORKER Nodes. Kubernetes requires a container runtime, and Docker is a popular choice. To install Docker, run the following commands:

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

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) \
  stable"

Installing Docker

apt-get update && sudo apt-get install \
  containerd.io=1.6.24-1 \
  docker-ce=5:20.10.24~3-0~ubuntu-$(lsb_release -cs) \
  docker-ce-cli=5:20.10.24~3-0~ubuntu-$(lsb_release -cs)

For example, The output terminal is as below:

Setting up the Docker daemon

cat <<EOF | sudo tee /etc/docker/daemon.json
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF

mkdir -p /etc/systemd/system/docker.service.d

Start and enable the docker

systemctl daemon-reload
systemctl enable docker
systemctl restart docker
systemctl status docker

Install Kubeadm, Kubelet, and Kubectl

Add the Kubernetes repository and install Kubeadm, Kubelet, and Kubectl

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

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

Installing Kubeadm, Kubelet, Kubectl

apt-get update
apt-get install -y kubelet kubeadm kubectl

apt-mark hold kubelet kubeadm kubectl

Start and enable Kubelet

systemctl daemon-reload
systemctl enable kubelet
systemctl restart kubelet
systemctl status kubelet

Initializing CONTROL-PLANE

Run it on MASTER Node only. On your master node, initialize the Kubernetes cluster with the command below:

kubeadm init

Make note of the kubeadm join command that’s provided at the end; you’ll need it to join worker nodes.

Installing POD-NETWORK add-on

Run it on MASTER Node only

For kubectl

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

Installing “Weave CNI” (Pod-Network add-on)

kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"

NOTE: There are multiple CNI Plug-ins available. You can install a choice of yours. In the case above commands don’t work, try checking the below link for more info

Joining Worker Nodes

Run it on WORKER Node only

On your worker nodes, use the kubeadm join command from above kubeadm init output to join them to the cluster.

kubeadm join <...>

Run this command IF you do not have the above join command and/or create a NEW one.

kubeadm token create --print-join-command

Verify the Cluster

On the master node, ensure your cluster is up and running

kubectl get nodes

You should see the master node marked as “Ready” and any joined worker nodes.

Conclusion

Congratulations! You’ve successfully installed Kubernetes using Kubeadm on Ubuntu. With your Kubernetes cluster up and running, you’re ready to deploy and manage containerized applications and services at scale.

Kubernetes offers vast capabilities for container orchestration, scaling, and management. As you become more familiar with Kubernetes, you can explore advanced configurations and features to optimize your containerized environment.

I hope will this your helpful. Thank you for reading the DevopsRoles page!

Additional Resources:

• Kubernetes Documentation
• Kubeadm Documentation
• Docker Documentation
• Calico Documentation