Set up Kubernetes with Virtualbox

Seeing that there are so much hype about Kubernetes, I decided to try it myself and see what it could do.

As I am trying to learn as much as I can about the mechanics behind it, I decided to create VMs in VirtualBox to have the experience of setting up Kubernetes by scratch.

I came upon this guide detailing the steps of doing so. Below are the documentation of my learning progress.

Setup the VMs

Create host only network

Create first VM (kubemaster)

I created a VM with

• system: Ubuntu server 18.04
• CPU: 1
• Memory: 1Gb

disable swap

It is recommended to disable the swap on the nodes, see reasons here

1. list swap files with cat /proc/swaps
2. Turn off all swap devices and files with swapoff -a
3. Remove any matching reference found in /etc/fstab

source

Install docker

I followed the official documentation on how to install docker found here

Clone 2 VMs (worker1, worker2)

make 2 clones of the kubemaster VM in VirtualBox

Configure the VMs

For quick development purposes I configured the VMs so that they each have two networks:

• Nat: for connection to the host computer.
• host-only network: to communicate with each other

Configure port forwarding for the NAT

In VirtualBox, I set up the port forwarding for each VM so that when I ssh via three different ports, I can connect to each VM respectively.

Give each VM a static IP address in the host-only network

Edit the netplan configuration file and add the following under the ethernets section. Remember to change the addresses section to match your setting, and give each VM a unique IP.

enp0s8:
    dhcp4: no
    addresses: [192.168.56.100/24]

Here I have the following IPs to each VM:

• kubemaster: 192.168.56.100
• worker1: 192.168.56.101
• worker2: 192.168.56.102

You can check your configuration by making sure that you can ssh into each vm respectively via the host only network.

Configure the hostname

Follow the below steps to change the host name of each machine

1. edit the /etc/hostname file
2. change each occurrence in the /etc/hosts file
3. reboot

source

Result

Now I will have three machines configured as follows: (note that I changed the number of CPUs for kubemaster to 2)

Setup Kubernetes

Setup kubemaster

Install kubeadm on kubemaster

I followed this guide on installing kubeadm

Set up the control-plane

On the master, I ran the following to start up a cluster. Remember to change the --apiserver-advertise-address to match your settings, or else the pods won’t be able to find the master.

kubeadm init --apiserver-advertise-address=192.168.56.100 --pod-network-cidr=192.168.0.0/16

Since I am going to use Calico, I need to set the pod network using CIDR.

The setting means that the nodes are getting the IPs 192.168.56.100-102, and the Pods will get the IPs 192.168.0.0/16

After the kubeadm finished, you should see something like the following.

Your Kubernetes control-plane has initialized successfully!

It would also give you a command for kubeadm join, you must remember this command. Saving it is a good idea.

Setup Calico as the pod network

Install Calico with the following command

kubectl apply -f https://docs.projectcalico.org/v3.9/manifests/calico.yaml

Confirm that all of the pods are running with the following command.

watch kubectl get pods --all-namespaces

Wait until each pod has the STATUS of Running.

Setup the workers

Install kubeadm on worker

As with kubemaster, I followed this guide on installing kubeadm

Join the cluster

Remember the kubeadm join command you just saved? Run the command on the workers. Once finished, go back to the kubemaster and run watch kubectl get pods --all-namespaces. You should see your pods joining with the output something like below:

NAMESPACE     NAME                                       READY   STATUS              RESTARTS
  AGE
kube-system   calico-kube-controllers-6b9d4c8765-5997r   1/1     Running             0
  21m
kube-system   calico-node-hs55k                          1/1     Running             0
  21m
kube-system   calico-node-v6zh5                          1/1     Running             0
  21m
kube-system   calico-node-x4jjr                          1/1     Running             0
  16m
kube-system   coredns-6955765f44-8lthn                   1/1     Running             0
  34m
kube-system   coredns-6955765f44-q67vz                   1/1     Running             0
  34m
kube-system   etcd-kubemaster                            1/1     Running             0
  34m
kube-system   kube-apiserver-kubemaster                  1/1     Running             0
  34m
kube-system   kube-controller-manager-kubemaster         1/1     Running             0
  34m
kube-system   kube-proxy-84g22                           1/1     Running             0
  34m
kube-system   kube-proxy-mkt42                           1/1     Running             0
  16m
kube-system   kube-proxy-nvjcj                           1/1     Running             0
  32m
kube-system   kube-scheduler-kubemaster                  1/1     Running             0
  34m