In this post, we will provision VMs for a Kubernetes cluster consisting of a single master node and two worker nodes. This setup is a prerequisite for bootstrapping the Kubernetes cluster using kubeadm, which we will cover in the next post.

Prerequisites

Ensure the following tools are installed:

  1. Your Choice of VM Software – The hypervisor that runs the virtual machines.

    • Options include VirtualBox, VMware, or Virtual Machine Manager (libvirt).
    • I ran into issues when trying to do this with VirtualBox. For that reason, I am using Virtual Machine Manager (VMM) with the libvirt provider. This approach should also provide more transparency into the provisioning process.

  2. Vagrant – An automation tool to simplify VM creation and configuration.

    • Follow the installation guide on the Vagrant documentation based on your operating system. In this guide, I am using Ubuntu.

  3. Sufficient Host Machine Resources – Ensure your system meets these hardware requirements for smooth operation:

    • CPU: At least 6 cores (e.g., a quad-core with hyper-threading)
    • RAM: 16 GB or more
    • Disk Space: At least 100 GB of free space

Clone the Repository and Install Required Tools

Step 1: Install Virtual Machine Manager (VMM) and Libvirt Dependencies

Install the required packages for libvirt:

sudo apt-get update
sudo apt-get install -y qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virt-manager
sudo systemctl enable --now libvirtd
sudo usermod -aG libvirt $(whoami)
sudo usermod -aG kvm $(whoami)
newgrp libvirt

Step 2: Clone the Repository

Clone the repository containing the Vagrantfile:

git clone https://github.com/techiescamp/vagrant-kubeadm-kubernetes.git
cd vagrant-kubeadm-kubernetes

Step 3: Install Vagrant and the Libvirt Plugin

Install Vagrant and the libvirt plugin:

sudo apt-get install -y vagrant
vagrant plugin install vagrant-libvirt

Step 4: Verify Installation

Confirm that Vagrant and libvirt are correctly installed:

vagrant --version
virsh list --all

Modifying the Vagrantfile

The Vagrantfile provided by the repository is initially configured for VirtualBox. To run it with the libvirt provider, make the following modifications. The repository’s Vagrantfile typically uses a settings hash (defined in the file or a separate configuration file) for CPU and memory settings. If you’re unsure where these values come from, check the Vagrantfile or accompanying documentation in the repository.

  1. Set the Default Provider to Libvirt: Add this line at the top of the Vagrantfile:

    ENV['VAGRANT_DEFAULT_PROVIDER'] = 'libvirt'

  2. Enable NFS with Version 3: Update the synced folder configuration. For example:

    config.vm.synced_folder ".", "/vagrant", type: "nfs", nfs_version: "3", nfs_udp: false

  3. Update the Provider Settings: Modify the controlplane and node provider blocks to specify CPU, memory, and driver settings for libvirt. For example:

    controlplane.vm.provider "libvirt" do |libvirt|
  libvirt.cpus = settings["nodes"]["control"]["cpu"]
  libvirt.memory = settings["nodes"]["control"]["memory"]
  libvirt.machine_type = "pc"
  libvirt.driver = "qemu"
end

    And similarly for the worker nodes:

    node.vm.provider "libvirt" do |libvirt|
  libvirt.cpus = settings["nodes"]["workers"]["cpu"]
  libvirt.memory = settings["nodes"]["workers"]["memory"]
  libvirt.machine_type = "pc"
  libvirt.driver = "qemu"
end

Troubleshooting NFS Issues

If you encounter an NFS-related error such as:

mount -o vers=3,udp 192.168.121.1:/path/to/vagrant /vagrant
mount.nfs: requested NFS version or transport protocol is not supported for /vagrant

To resolve this:

  1. Edit /etc/default/nfs-kernel-server to disable NFS version 4:

    RPCMOUNTDOPTS="--manage-gids --no-nfs-version 4"

  2. Restart the NFS server:

    sudo systemctl restart nfs-kernel-server

Try vagrant up again after these changes.

Provisioning the Virtual Machines

  1. Bring Up the VMs:

    vagrant up

  2. Check the Status of VMs:

    vagrant status

  3. Connect to a VM: Use SSH to connect:

    vagrant ssh controlplane

Connect to the Virtual Machines

To access the VMs, use the vagrant ssh command:

  1. Connect to the Master Node:

    vagrant ssh controlplane

    Verify the connection by listing files:

    ls -la

  2. Exit the Node:
    Use the logout command to return to your local machine:

    logout

  3. Connect to the Worker Nodes:

    • e.g. Worker Node 1:
    vagrant ssh node01

    Check uptime:

    uptime

    Exit when done:

    logout

Shutting Down and Restarting the Cluster

To gracefully shut down all VMs:

vagrant halt

To restart them later:

vagrant up

In the next post, we will bootstrap the Kubernetes cluster using the kubeadm tool, and begin setting up the control plane components.