To set up a cluster on AWS using Kubeadm, you need the following:

• A compatible Linux host.

• 2 GB or more of RAM per machine and at least 2 CPUs.

• Full network connectivity between all machines in the cluster.

• Unique hostname for each host. Change hostname of the machines using hostnamectl.

• Ensure that certain ports are open on your machines.

• Disable swap. Disabling swap is essential for the kubelet to work properly.

• Install Containerd on all machines.

Kubernetes Setup Using Kubeadm In AWS EC2 instance

Prerequisites	Ubuntu:latest
1 - Control plane	t2.medium and above
2 - Worker nodes	t2.micro and above

Note: Open below required Ports In AWS Security Groups

Reference link : https://kubernetes.io/docs/reference/ports-and-protocols

Kubernetes Master Server required Port

Slave/worker nodes required Ports

Below steps are common for both master server and worker nodes.

Switch to root user

sudo -i

Use 'hostnamectl' command to change the hostname of both the server and worker nodes

hostnamectl set-hostname kubeserver = controlplane

hostnamectl set-hostname worker1 = worker1/node01

hostnamectl set-hostname worker2 = worker2/node02

To apply the changes, please log out of and then log back into the instances

sudo -i

we must disable swap in order for the kubelet to work properly

swapoff -a

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

Installing a container runtime

we can install containerd in multiple ways

from apt-get

sudo apt update

sudo apt install containerd
From the official binaries

Step 1: Installing containerd

Download the containerd-*.tar.gz archive from

https://github.com/containerd/containerd/releases

wget https://github.com/containerd/containerd/releases/download/v1.7.5/containerd-1.7.5-linux-amd64.tar.gz
extract it under /usr/local

tar Cxzvf /usr/local containerd-1.7.5-linux-amd64.tar.gz
setting up containerd as systemd service

mkdir -p /usr/local/lib/systemd/system wget -P /usr/local/lib/systemd/system/

https://raw.githubusercontent.com/containerd/containerd/main/containerd.service systemctl daemon-reload systemctl enable --now containerd

Step 2: Installing runc

Download the runc binary from https://github.com/opencontainers/runc/releases , and

install it as /usr/local/sbin/runc

wget https://github.com/opencontainers/runc/releases/download/v1.1.9/runc.amd64 install -m 755 runc.amd64 /usr/local/sbin/runc

Step 3: Installing CNI plugins

Download the cni-plugins-*.tgz archive from

https://github.com/containernetworking/plugins/releases , and extract it under /opt/cni/bin

wget https://github.com/containernetworking/plugins/releases/download/v1.3.0/cni-plugins-linux-amd64- v1.3.0.tgz

mkdir -p /opt/cni/bin

tar Cxzvf /opt/cni/bin cni-plugins-linux-amd64-v1.3.0.tgz

Step 4: Installing crictl [Cli tool]

wget https://github.com/kubernetes-sigs/cri-tools/releases/download/v1.28.0/crictlv1.28.0-linux-amd64.tar.gz

sudo tar zxvf crictl-v1.28.0-linux-amd64.tar.gz -C /usr/local/bin rm -f crictl-v1.28.0-linux-amd64.tar.gz

cat <<EOF | sudo tee /etc/crictl.yaml

runtime-endpoint: unix:///run/containerd/containerd.sock

image-endpoint: unix:///run/containerd/containerd.sock

timeout: 2

debug: false

pull-image-on-create: false

EOF

Forwarding IPv4 and letting iptables see bridged traffic

• Execute the below mentioned instructions

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
overlay
br_netfilter
EOF
sudo modprobe overlay
sudo modprobe br_netfilter
# sysctl params required by setup, params persist across reboots
cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward = 1
EOF
# Apply sysctl params without reboot
sudo sysctl --system
sysctl net.bridge.bridge-nf-call-iptables net.bridge.bridge-nf-call-ip6tables 
net.ipv4.ip_forward
modprobe br_netfilter
sysctl -p /etc/sysctl.conf

Verify that the br_netfilter, overlay modules are loaded by running the following

lsmod | grep br_netfilter

lsmod | grep overlay

Installing kubeadm:

Below steps are common for both master server and worker nodes

Update the APT package index and install the necessary packages to enable the use of

the Kubernetes APT repository

Sudo apt-get update

apt-get update && sudo apt-get install -y apt-transport-https curl
Download the public signing key for the Kubernetes package repositories

mkdir -p /etc/apt/keyrings/

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.28/deb/Release.key | sudo gpg --

dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
Add the appropriate Kubernetes apt repository:

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
Update the apt package index, install kubelet, kubeadm and kubectl

sudo apt-get update

sudo apt-get install -y kubelet kubeadm kubectl
apt-mark hold will prevent the package from being automatically upgraded or

removed.

apt-mark hold kubelet kubeadm kubectl containerd

From here below steps are only for master server. make sure you execute them only on master.

Downloading component images on master.

kubeadm config images pull
Initializing your control-plane node

The control-plane node is the machine where the control plane components run,

including etcd (the cluster database) and the API Server (which the kubectl command

line tool communicates with)

If you have plans to upgrade this single control-plane kubeadm cluster to high

availability you should specify the --control-plane-endpoint to set the shared endpoint

for all control-plane nodes. Such an endpoint can be either a DNS name or an IP

address of a load-balancer.

kubeadm init

Note: Copy the join token and save it

kubeadm join 172.31.24.155:6443 --token yo1pa1.zky7ws22p1kk1e22 \

--discovery-token-ca-cert-hash

sha256:86ac30b64f12f6f24b10ac36bb9a881ee5c813321d894871507d90501c037871

To start using your cluster, you need to run the following as a regular user:

mkdir -p $HOME/.kube

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf

To verify, if kubectl is working or not, run the following command

You will notice from the previous command, that all the pods are running except one: ‘coredns’.

For resolving this we will install a # pod network
Installing pod network

Reference: https://kubernetes.io/docs/concepts/cluster-administration/addons/

weave net pod network, execute below command

kubectl apply -f https://github.com/weaveworks/weave/releases/download/v2.8.1/weave-daemonset-k8s.yaml

To check the status of kube server, run this command

kubectl get nodes

Add Worker Machines to Kubernetes Master

Copy kubeadm join token from server-command-line and execute in Worker Nodes to

join nodes to cluster

kubeadm join 172.31.24.155:6443 --token yo1pa1.zky7ws22p1kk1e22 \

--discovery-token-ca-cert-hash

sha256:86ac30b64f12f6f24b10ac36bb9a881ee5c813321d894871507d90501c037871

This node has joined the cluster:

* Certificate signing request was sent to apiserver and a response was received.

* The Kubelet was informed of the new secure connection details.

To verify the worker node status, run 'kubectl get nodes' on the control-plane

kubectl get nodes

Kubernetes Setup Using Kubeadm