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Luke
Luke

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Deploy Kubernetes On-Premises From Zero

#kubernetes

Resource Preparation

Name IP Role RAM CPU OS
k8s-master-1 192.168.1.111 Control Plane 3 2 Ubuntu 22.04 LTS
k8s-master-2 192.168.1.112 Worker 3 2 Ubuntu 22.04 LTS
k8s-master-3 192.168.1.113 Worker 3 2 Ubuntu 22.04 LTS

Implementation Steps

1) Update system 

sudo apt update -y && sudo apt upgrade -y
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2) Add hosts (above all 3 virtual machines)

Open file host to config ip address

vim /etc/hosts/
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Add those configs into file

192.168.1.111 k8s-master-1
192.168.1.112 k8s-master-2
192.168.1.113 k8s-master-3
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Saved and check

ping <ip-addr>
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3) Create a new user

We should create/switch to another user (avoid using root) to install kubernetes

Create devops user and add to sudo group

adduser devops
usermod -aG sudo devops
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Switch to devops

su devops
cd /home/devops
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4) Turn off swap

Because Kubernetes require actual RAM to ensure about performance and stable

# turn off swap forever
sudo sed -i '/swap/s/^/#/' /etc/fstab
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5) Download and add module into kernel

System will download overlay & br_netfilter package manually, this is two modules which require for k8s implement

  • overlay: Support overlay filesystem, it's necessary for containerd to manage container image.

  • br_netfilter: Allow filter network package on bridge network, it's very important for Kubernetes to handle traffic between container.

sudo modprobe overlay
sudo modprobe br_netfilter
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To make system automatically install two modules above after restart, we need modify config file by command below

sudo tee /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF
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6) Config network

Those config to make sure:

  • Kubernetes can manage traffic between containers and Pods.
  • Firewall rules can apply to traffic via bridge network.
  • The system can routing package between nodes in cluster. 
echo "net.bridge.bridge-nf-call-ip6tables = 1" | sudo tee -a /etc/sysctl.d/kubernetes.conf
echo "net.bridge.bridge-nf-call-iptables = 1" | sudo tee -a /etc/sysctl.d/kubernetes.conf
echo "net.ipv4.ip_forward = 1" | sudo tee -a /etc/sysctl.d/kubernetes.conf
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Apply sysctl config

sudo sysctl --system
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7) Install docker 

sudo apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificates
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/docker.gpg
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
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8) Install & config containerd

This is container runtime which is use by Kubernetes for manage container

sudo apt install -y containerd.io
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After installed, we need config containerd use Systemd to manage resource group (cgroup) => This make resource management become consistent.

containerd config default | sudo tee /etc/containerd/config.toml >/dev/null 2>&1
sudo sed -i 's/SystemdCgroup = false/SystemdCgroup = true/g' /etc/containerd/config.toml
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Restart containerd

sudo systemctl restart containerd
sudo systemctl enable containerd
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9) Install Kubernetes package

Config to download from legit source

echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /" | sudo tee /etc/apt/sources.list.d/kubernetes.list
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
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Install packages (kubelet, kubeadm, kubectl)

sudo apt install -y kubelet kubeadm kubectl
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For avoid auto upgrade version => Ensure package versions are consistent.

sudo apt-mark hold kubelet kubeadm kubectl
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Deploy model (1 master - 2 worker)

1master2workers

Standard model

Init Kubernetes on master node 

sudo kubeadm init
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.25.0/manifests/calico.yaml
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After the initial setup, it'll have command follow format below - use it to add worker

sudo kubeadm join <ip-master-node>:6443 --token <your_token> --discovery-token-ca-cert-hash <your_sha>
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Add worker node

Copy command from master node and paste it to machine where role determine is worker role (maybe you need to run it with sudo)

Verify

Run kubectl get node -o wide in master node to check worker added

verify-workers

Example output

Conclusion

Just one of over 35 ways to install Kubernetes. In the future, to add more workers to your system, simply run

sudo kubeadm join <ip-master-node>:6443 --token <your_token> --discovery-token-ca-cert-hash <your_sha>
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In the next post of series, I will show you how to use cloud for Kubernetes
Happy Coding!

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