Kubernetes installation on bare-metal

Kubernetes installation on bare-metal, Ubuntu 20.04 is used for master and Ubuntu 18.04 used for worker nodes. You can use VM as a node. kubeadm=1.21.1-00 kubelet=1.21.1-00 kubectl=1.21.1-00

Required steps for the master and each worker node

Disable the swap (Only once) and check it from /etc/fstab.

swapoff -a

DOCKER

Google apt repository key added (Only once).

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -

Install Docker.

sudo apt-get update
sudo apt-get install -y docker.io

Configure managements of the container's cgroups.

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 daemon-reload
sudo systemctl restart docker

Enable it to run the docker service when the system start.

sudo systemctl enable docker.service
systemctl restart docker

KUBERNETES

Kubernetes apt repository added (Only once).

echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee -a /etc/apt/sources.list.d/kubernetes.list

Install Kubernetes.

sudo apt update && sudo apt install -y kubeadm=1.21.1-00 kubelet=1.21.1-00 kubectl=1.21.1-00

Enable it to run the kubelet service when the system start.

sudo systemctl enable kubelet.service
systemctl restart kubelet

Check the status of Kubelet and Docker services.

sudo systemctl status kubelet.service   
sudo systemctl status docker.service

Required steps for the master

Download calico.yaml file and determine pod-network-cidr according to calico.yaml file.

wget https://docs.projectcalico.org/v3.14/manifests/calico.yaml
sudo kubeadm init --apiserver-advertise-address=10.40.30.100 --pod-network-cidr={CALICO_IP}/16  --ignore-preflight-errors=all

Create a user that has authority to reach API server.

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

Create the pod network using downloaded calico.yaml.

sudo kubectl --kubeconfig=/etc/kubernetes/admin.conf create -f calico.yaml

To get and list worker node token.

kubeadm token create --print-join-command
kubeadm token list

Check kubernetes system pods, services and nodes.

kubectl get pods --all-namespaces -o wide 
kubectl get svc --all-namespaces
kubectl get nodes -o wide 
sudo systemctl status kubelet.service

Regenerate a token for worker nodes.

kubeadm token create

Required steps for each worker node

Initializes a Kubernetes worker node and joins it to the cluster while using given token from master.

sudo kubeadm join {IP}:6443 --token{TOKEN} --discovery-token-ca-cert-hash <ca_cert_hash>
kubeadm join --token 702ff6.bc7aacff7aacab17 174.138.15.158:6443 --discovery-token-ca-cert-hash sha256:68bc22d2c631800fd358a6d7e3998e598deb2980ee613b3c2f1da8978960c8ab 

Remove Docker and Kubernetes

Uninstall Docker

sudo apt-get purge docker-ce docker-ce-cli containerd.io docker.io
sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd
sudo apt remove docker-*

Uninstall K8s

sudo kubeadm reset
sudo apt-get purge kubeadm kubectl kubelet kubernetes-cni kube*
sudo rm -rf ~/.kube