Create a Kubernetes (k8s) cluster among Virtual Machines with Ansible and Incus

The repository contains scripts to quickly create a k8s cluster among virtual machines on a single physical node. It contains the following main components:

• create_incus-net.sh: creates a bridged network within a single node
• create_vms.sh: creates a VM
• ansible/: contains Ansible playbooks to initialize a Kubernetes cluster using the VMs above

Requirements

Software packages:

• incus
• ansible

Incus images:

• k8s in the local: image registry (in the future to be pushed upstream)

How to run

There are two dependent steps:

1. Create VMs with Incus
2. Setup Kubernetes cluster

VM creation

Login on the node where you want to host the VMs. Edit the variable NET=kashef-albaraa in the script create_incus-net.sh. Then:

sudo ./create_incus-net.sh

Check if the network has been created successfully and take note of the IP range assigned to it.

$ sudo incus network list

+-----------------+----------+---------+-----------------+---------------------------+-------------+---------+---------+
|      NAME       |   TYPE   | MANAGED |      IPV4       |           IPV6            | DESCRIPTION | USED BY |  STATE  |
+-----------------+----------+---------+-----------------+---------------------------+-------------+---------+---------+
+-----------------+----------+---------+-----------------+---------------------------+-------------+---------+---------+
| kashef0         | bridge   | YES     | 10.112.180.1/24 | fd42:52dd:8110:19c7::1/64 |             | 3       | CREATED |
+-----------------+----------+---------+-----------------+---------------------------+-------------+---------+---------+
| kashef-albaraa  | bridge   | YES     | 10.180.100.1/24 | fd42:a79b:5816:4cc::1/64  |             | 3       | CREATED |
+-----------------+----------+---------+-----------------+---------------------------+-------------+---------+---------+
| kashef-cornaca  | bridge   | YES     | 10.178.48.1/24  | fd42:de83:6d94:fe2b::1/64 |             | 3       | CREATED |
+-----------------+----------+---------+-----------------+---------------------------+-------------+---------+---------+

Edit the script create_vms.sh, specify the name of the VM you want to create and the name of the network it must be connected to (e.g., kashef-albaraa).

Then run:

sudo ./create_vms.sh

NOTE: If the image k8s is not available in your setup, you can start from a clean ubuntu image. However, you need to modify the Ansible scripts to install kubeadm, kubectl, docker and related dependencies.

Check if the image has been created:

sudo incus list

Kubernetes setup with Ansible

Login on the node where you installed your Ansible client. The ansible/ folder contains automation scripts to initialize and join a multi-node Kubernetes cluster.

Create inventory

Create an inventory file with your target machines. Duplicate inventory-cornaca.yaml and edit according to the VMs you created.

Run playbooks

ansible-playbook -K -i <inventory name> <playbook>

Use the two Ansible playbooks in the order specified below:

1. controller.yaml
2. workers.yaml

Replace <inventory name> with your new inventory.

Advanced usage

Depending on your needs, you may want to perform some steps manually, but still use Ansible for other tasks. The playbooks contain tags: here and there in the code. You can add others.

Then run ansible-playbook with the option -t <tag name> to filter the subset of tasks you want to execute.