Create VMs for hosting a Kubernetes cluster

1. Introduction

Before installing a Kubenretes cluster, we need to install the VMs first. We will use Vagrant to install those machines using libvirt.

2. Architecture

Host	IP Address	Admin	Etcd	Single Master	Multi Master	Worker
strasbourg.europe	192.168.20.141	always
paris.europe	192.168.20.52		always	always	initial
berlin.europe	192.168.20.55		when master		join
roma.europe	192.168.20.67		when master		join
lisboa.europe	192.168.20.91					always
madrid.europe	192.168.20.92					always
amsterdam.europe	192.168.20.93					always

3. Pre requisites

• A strong computer with at least 8 vCPUs and 16GB RAM
• Libvirt installed
• Vagrant installed to deploy and configure debian "buster" VMs using Libvirt

3.1 Libvirt change default network settings

Before moving one, we have to change the default network in libvirt.
Why ? Because of a problem during etcd installation. Etcd was not listening on my subnet 192.168.20.0/24 but was binded to an other subnet.

virsh net-edit default

Change ip address and range to reflect our default network used in vagrant 192.168.20.0/24

<network>
  <name>default</name>
  <uuid>142e6412-86a4-4d44-8b15-833562417d29</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:e4:48:bb'/>
  <ip address='192.168.20.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.20.2' end='192.168.20.254'/>
    </dhcp>
  </ip>
</network>

After this change we apply with :

virsh net-start default

A "ping paris" on the paris.europe host should produce 192.168.20.52

4. Create VMs

Move to vagrant/libvirt/demo directory (assuming git repo is installed in ~/k8s_vagrant) and create the VMs using "vagrant up" (moving up). Note : you password will be prompted for sudo operation.

cd ~/k8s_vagrant/vagrant/libvirt/demo
vagrant up
[sudo] Password for xxxxx :

Allow transparent ssh for user vagrant for all VM :

./ssh_allow_all.sh

Now you are able to connect the VM using vagrant account :

ssh vagrant@192.168.20.141

Now all the VMs are up and running. If you want to stop the VMs :

vagrant halt -f

or just one VM :

vagrant halt strasbourg.europe -f

If you want to start the VMs :

vagrant up

or just one VM :

vagrant up strasbourg.europe

If you want to destroy all the VMs :

vagrant destroy -f

or just one VM :

vagrant destroy strasbourg.europe -f