Kubeadm Cluster Setup

Part A - Controller and Worker Nodes ( on 3 servers )

• Configure Network Prerequisites

Container Runtimes

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

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

lsmod | grep br_netfilter
lsmod | grep overlay

• Verify that the net.bridge.bridge-nf-call-iptables, net.bridge.bridge-nf-call-ip6tables, and net.ipv4.ip_forward system variables are set to 1 in your sysctl config by running the following command:

sysctl net.bridge.bridge-nf-call-iptables net.bridge.bridge-nf-call-ip6tables net.ipv4.ip_forward

Configure Container Runtime

• Set up Docker's apt repository.

Add Docker's official GPG key:

sudo apt-get update sudo apt-get install ca-certificates curl sudo install -m 0755 -d /etc/apt/keyrings sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc sudo chmod a+r /etc/apt/keyrings/docker.asc

Add the repository to Apt sources:

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt-get update

Install the Docker packages.

sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

add sudo permission to docker

sudo usermod -aG docker ubuntu
newgrp docker
docker images

Make daemon file for docker to aviod service errors later

sudo mkdir /etc/docker
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

sudo systemctl enable docker
sudo systemctl daemon-reload
sudo systemctl restart docker

Switch-off the swap in all the nodes

sudo swapoff -a
sudo vi /etc/fstab

Configure the containerd runtime environment.

Login as root:

sudo su -

Create a default containerd configuration file:

• containerd config default > /etc/containerd/config.toml
• Open config.toml in a text editor:

vi /etc/containerd/config.toml

• Change the value of SystemdCgroup from false to true (it should be visible around line number 125 in config.toml): SystemdCgroup = true

Restart containerd

systemctl restart containerd

Exit the sudo mode:

exit

Installing kubeadm, kubelet and kubectl

kubeadm: the command to bootstrap the cluster.

kubelet: the component that runs on all of the machines in your cluster and does things like starting pods and containers.

kubectl: the command line util to talk to your cluster.

sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.28/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg

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

sudo apt-get update

sudo apt-get install -y kubelet kubeadm kubectl

• kubeadm version
• kubelet --version
• kubectl version

sudo apt-mark hold kubelet kubeadm kubectl

---

Part B - Controller Node ONLY ( Master Node )

(RUN AS ROOT) Initiate API server:

sudo su -
kubeadm init --apiserver-advertise-address=*<ControllerVM-PrivateIP>* --pod-network-cidr=10.244.0.0/16 
exit

(RUN AS NORMAL USER) Add a user for kube config:

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

(RUN AS NORMAL USER) Deploy Weave network:

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

(RUN AS ROOT) Create cluster join command:

sudo su -
kubeadm token create --print-join-command

kubeadm join <**172.31.8.221:6443**> --token 9ep3pf.ilxyyzjqku0q2il5 --discovery-token-ca-cert-hash sha256:9c482bb9d478c4ec10ce419bc27948be3eb9b38fb5c6595f135f419385fbb13e

kubectl get nodes

---

Part C - Worker Nodes ONLY ( In Worker Node )

connecting nodes to master plane

• Copy the output of the cluster join command from the previous step and run on the VMs designated as the worker nodes.

sudo su -
kubeadm join 172.31.8.221:6443 --token 9ep3pf.ilxyyzjqku0q2il5 --discovery-token-ca-cert-hash sha256:9c482bb9d478c4ec10ce419bc27948be3eb9b38fb5c6595f135f419385fbb13e

Note:we need to run the above command in our nodes to join them in cluster