4.3. Kubeadm

1. Prerequisite

Before building a Kubernetes cluster, install the necessary components to the cluster.

Please refer to Install Prerequisite and install the necessary components to the cluster.

Change the configuration of the network for Kubernetes.

sudo modprobe br_netfilter

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
br_netfilter
EOF

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

2. Setup Kubernetes Cluster

• kubeadm : Automates the installation process by registering kubelet as a service and issuing certificates for communication between cluster components.
• kubelet : Container handler responsible for starting and stopping container resources.
• kubectl : CLI tool used to interact with and manage Kubernetes clusters from the terminal.

Install kubeadm, kubelet, and kubectl using the following commands. It's important to prevent accidental changes to the versions of these components, as it can lead to unexpected issues.

sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl &&
sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg &&
echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list &&
sudo apt-get update
sudo apt-get install -y kubelet=1.21.7-00 kubeadm=1.21.7-00 kubectl=1.21.7-00 &&
sudo apt-mark hold kubelet kubeadm kubectl

Check if kubeadm, kubelet, and kubectl are installed correctly.

mlops@ubuntu:~$ kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.7", GitCommit:"1f86634ff08f37e54e8bfcd86bc90b61c98f84d4", GitTreeState:"clean", BuildDate:"2021-11-17T14:40:08Z", GoVersion:"go1.16.10", Compiler:"gc", Platform:"linux/amd64"}

mlops@ubuntu:~$ kubelet --version
Kubernetes v1.21.7

mlops@ubuntu:~$ kubectl version --client
Client Version: version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.7", GitCommit:"1f86634ff08f37e54e8bfcd86bc90b61c98f84d4", GitTreeState:"clean", BuildDate:"2021-11-17T14:41:19Z", GoVersion:"go1.16.10", Compiler:"gc", Platform:"linux/amd64"}

Now we will use kubeadm to install Kubernetes.

kubeadm config images list
kubeadm config images pull

sudo kubeadm init --pod-network-cidr=10.244.0.0/16

Through kubectl, copy the admin certificate to the path $HOME/.kube/config to control the Kubernetes cluster.

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

Install CNI. There are various kinds of CNI, which is responsible for setting up the network inside Kubernetes, and in MLOps for All, flannel is used.

kubectl apply -f https://raw.githubusercontent.com/flannel-io/flannel/v0.13.0/Documentation/kube-flannel.yml

There are two types of Kubernetes nodes: Master Node and Worker Node. For stability, it is generally recommended that only tasks to control the Kubernetes cluster are run on the Master Node, however this manual assumes a single cluster, so all types of tasks can be run on the Master Node.

kubectl taint nodes --all node-role.kubernetes.io/master-

3. Setup Kubernetes Client

Copy the kubeconfig file created in the cluster to the client to control the cluster through kubectl.

mkdir -p $HOME/.kube
scp -p {CLUSTER_USER_ID}@{CLUSTER_IP}:~/.kube/config ~/.kube/config

4. Install Kubernetes Default Modules

Please refer to Setup Kubernetes Modules to install the following components:

• helm
• kustomize
• CSI plugin
• [Optional] nvidia-docker, nvidia-device-plugin

5. Verify Successful Installation

Finally, check if the nodes are Ready and verify the OS, Docker, and Kubernetes versions.

kubectl get nodes

When the node is in the "Ready" state, the output will be similar to the following:

NAME     STATUS   ROLES                  AGE     VERSION
ubuntu   Ready    control-plane,master   2m55s   v1.21.7

6. References

• kubeadm