Kubernetes Bare Metal

https://www.digitalocean.com/community/tutorials/bare-metal-kubernetes

You probably want to use cloud-init like this Ubuntu 24.04

cloud-init configuration for provisioning Kubernetes nodes on Ubuntu 24.04 LTS.

This script handles:

• Disabling swap (required by kubelet)
• Enabling necessary kernel modules (overlay, br_netfilter)
• Setting required sysctl networking parameters
• Installing and configuring containerd with the SystemdCgroup driver enabled
• Adding the official pkgs.k8s.io repository (configured for Kubernetes v1.30)
• Installing and locking (apt-mark hold) kubelet, kubeadm, and kubectl

---

Cloud-Init YAML (user-data)

#cloud-config
package_update: true
package_upgrade: false

packages:
  - apt-transport-https
  - ca-certificates
  - curl
  - gpg
  - containerd

write_files:
  # Enable required kernel modules for container networking
  - path: /etc/modules-load.d/k8s.conf
    permissions: '0644'
    content: |
      overlay
      br_netfilter

  # Set sysctl rules for iptables bridge & IP forwarding
  - path: /etc/sysctl.d/k8s.conf
    permissions: '0644'
    content: |
      net.bridge.bridge-nf-call-iptables  = 1
      net.bridge.bridge-nf-call-ip6tables = 1
      net.ipv4.ip_forward                 = 1

runcmd:
  # 1. Disable swap immediately and persistently across reboots
  - swapoff -a
  - sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

  # 2. Load kernel modules and apply sysctl settings
  - modprobe overlay
  - modprobe br_netfilter
  - sysctl --system

  # 3. Configure containerd with SystemdCgroup enabled
  - mkdir -p /etc/containerd
  - containerd config default | tee /etc/containerd/config.toml > /dev/null
  - sed -i 's/SystemdCgroup = false/SystemdCgroup = true/g' /etc/containerd/config.toml
  - systemctl restart containerd
  - systemctl enable containerd

  # 4. Add official Kubernetes v1.30 apt repository
  - mkdir -p -m 755 /etc/apt/keyrings
  - curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
  - chmod 644 /etc/apt/keyrings/kubernetes-apt-keyring.gpg
  - echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /' | tee /etc/apt/sources.list.d/kubernetes.list

  # 5. Install Kubernetes binaries and prevent auto-upgrades
  - apt-get update
  - apt-get install -y kubelet kubeadm kubectl
  - apt-mark hold kubelet kubeadm kubectl
  - systemctl enable --now kubelet

---

Next Steps After Boot

Once your machine finishes running cloud-init, choose your role:

For the Control Plane (Master Node)

Initialize the cluster with your control plane IP and preferred pod CIDR (e.g., Flannel/Calico):

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

For Worker Nodes

Run the kubeadm join command provided at the end of your control plane's kubeadm init output.