Deploying Kubernetes on Bare Metal the Hard Way

Here’s a comprehensive checklist for setting up a Kubernetes Master Node. Follow this step-by-step process to ensure a smooth setup:

Preliminary Setup

System Requirements:
- OS: Ubuntu 20.04+, CentOS 7+, Debian 10+.
- CPU: Minimum 2 cores.
- RAM: At least 2 GB (4 GB recommended).
- Disk: Minimum 10 GB free space.
- Network: Stable connectivity with a static or reserved IP address.

Disable Swap:

sudo swapoff -a
sudo sed -i '/ swap / s/^/#/' /etc/fstab

Install Required Packages:

Update system:
```
sudo apt update && sudo apt upgrade -y
```

Install dependencies:

sudo apt install -y apt-transport-https ca-certificates curl software-properties-common

Configure Kernel Modules:

sudo modprobe overlay
sudo modprobe br_netfilter

Persist the modules:

echo -e "overlay\nbr_netfilter" | sudo tee /etc/modules-load.d/k8s.conf

Set Kernel Parameters for Kubernetes: Add the following to /etc/sysctl.d/k8s.conf:

net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward = 1

Apply the changes:

sudo sysctl --system

Install Docker and Container Runtime

Install Docker (Optional if using containerd):

Add Docker’s official GPG key:

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

Add the Docker repository:

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

Install Docker:

sudo apt install -y docker-ce docker-ce-cli containerd.io

Install containerd (Preferred for Kubernetes):

Install:
```
sudo apt install -y containerd
```

Configure containerd:

sudo mkdir -p /etc/containerd
containerd config default | sudo tee /etc/containerd/config.toml

Enable SystemdCgroup in /etc/containerd/config.toml:
```
SystemdCgroup = true
```
Restart containerd:
```
sudo systemctl restart containerd
```

Install Kubernetes Components

Add Kubernetes Repository:

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"

Install kubeadm, kubelet, and kubectl:

sudo apt install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

Check Installed Versions:

kubeadm version
kubectl version --client
kubelet --version

Initialize the Kubernetes Cluster

Initialize Master Node:

kubeadm init --apiserver-advertise-address=<STATIC_IP> --pod-network-cidr=10.244.0.0/16

Replace <STATIC_IP> with the master node’s IP.

Set Up kubeconfig for kubectl:

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

Verify Node Status:
```
kubectl get nodes
```

Install Pod Network

Deploy a Network Add-on (Choose One):

Flannel:

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

Calico:

kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

Verify Pod Network Setup:
```
kubectl get pods --all-namespaces
```

Post-Installation Setup

Ensure Node Is Ready: Confirm the master node is in the Ready state:
```
kubectl get nodes
```
Enable Scheduling on Master Node (Optional for Single Node Cluster):
```
kubectl taint nodes --all node-role.kubernetes.io/master-
```
Backup Cluster Configurations: Save the kubeadm init join command for adding worker nodes later.
Check API Server Logs:
```
journalctl -u kubelet -f
```

Summary Checklist

Step	Command/Description	Status
Disable Swap	`swapoff -a`	✅
Install Docker/Containerd	Install and configure container runtime	✅
Load Kernel Modules	Configure overlay, br_netfilter, etc.	✅
Install Kubernetes Components	kubeadm, kubelet, kubectl	✅
Initialize Master Node	`kubeadm init`	✅
Configure kubectl	Copy and set permissions for kubeconfig	✅
Install Pod Network	Apply Flannel or Calico	✅
Verify Cluster	`kubectl get nodes` and `kubectl get pods --all-namespaces`	✅

Following this checklist will ensure your Kubernetes master node is correctly set up and operational. Let me know if you encounter any issues!