Set up a Kubernetes Cluster with kubeadm

5 min readFeb 8, 2022

In this article, we are going to cover How to Install Kubernetes Cluster on Ubuntu 20.04 LTS with kubeadm in cloud platforms like Amazon EC2, Azure VM, Google Cloud Compute, etc.

This is tested on Google cloud Platform VM.

Prerequisites

Three Ubuntu servers 20.04 with at least 4GB RAM and 2 vCPUs each.

SSH Access with sudo privileges.
Firewall Ports/Inbound Traffic Ports should open for Kubernetes Cluster.

Master Node Ports: 2379,6443,10250,10251,10252
Worker Node Ports: 10250,30000–32767.
Default port range for NodePort Services -30000–32767.

Setup Steps:

Disable the swap and make sure be a net filter module is installed.
we will need to install the container runtime interface ie. docker
Install kubeadm, kubelet, and kubectl: kubeadm is building tools that help to bootstrap the cluster,
kubelet is an agent that runs on each node to make sure that containers are running in a Pod,
kubectl allows you to run commands against Kubernetes clusters.
Initialize the Kubernetes cluster which creates certificates, pods, services, and other resources.
Installing wave network add-on.
Finally, join the worker nodes to the Kubernetes cluster.

Step1) Disable Swap (Run it on MASTER & WORKER Nodes)

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

1a) Bridge Traffic

$ lsmod | grep br_netfilter 
$ sudo modprobe br_netfilter$ cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF$ sudo sysctl --system

lsmod | grep br_netfilter will load the module.
To load it explicitly calls sudo modprobe br_netfilter.
As a requirement for your Linux Node’s iptables to correctly see bridged traffic.
You should ensure net.bridge.bridge-nf-call-iptables is set to 1 in your sysctl configBridge Traffic.

Step2) Install Docker (Run it on MASTER & WORKER Nodes)

$ apt-get update 
$ apt install docker.io
$ systemctl start docker

If you facing any issues, Click here to install docker.

2a) 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

2b) Reload, enable and restart the docker service

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

Make sure the docker service is running.

Step3) Install kubeadm, kubelet, and kubectl (Run it on MASTER & WORKER Nodes)

$ 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

3a) Installing Kubeadm, Kubelet, Kubectl:

$ apt-get update
$ apt-get install -y kubelet kubeadm kubectl
$ apt-mark hold kubelet kubeadm kubectl

3b) Start and enable Kubelet

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

Step4) Initializing CONTROL-PLANE (Run it on MASTER Node only)

$ kubeadm init --pod-network-cidr 10.0.0.0/16

As the above output mentioned copy the token in your notepad, we will need to join worker/slave to the master node.

4a) Create new ‘.kube’ configuration directory and copy the configuration ‘admin.conf’ from ‘/etc/kubernetes’ directory.

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

Step5) Installing POD-NETWORK add-on (Run it on MASTER Node only)

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

Step6) Next Join two worker nodes to master (Run it on both worker nodes)

Paste the Join command from the above kubeadm init output

$kubeadm join 10.128.0.9:6443 --token 21dg74.rkaqfcksuut150xm \
>         --discovery-token-ca-cert-hash sha256:69cffbab4446f21047711bd074074747daa4211508c973931c0c7f177db4f108

6a) Run this command IF you do not have the above join command.

$ kubeadm token create — print-join-command

6b) Check the joined nodes

$ kubectl get nodes -o wide

Also, check