k3s-install.md

Installing K3s on Raspberry Pi Cluster

Description

This article will document how to deploy K3s to a cluster of Raspberry Pis.

Requirements

I am using the following:

• One (1) Laptop (Running Ubuntu 21.10)
• Three (3) Raspberry Pis running Raspberry Pi OS, 64-bit (Debian 10 buster)
  • Two (2) raspberry pi model 4s, with 8gb RAM
  • One (1) Raspberry Pi 400 with 4gb RAM
  • Each Pi is using a Samsung T7 SSD connected via USB 3.0 for storage

Before you start

Make sure that each Raspberry Pi is running and accessible on the network. You will need a list of each Pi's IP address.

Install Ansible on the Laptop¹

To configure the PPA on your machine and install Ansible run these commands:¹

$ sudo apt update
$ sudo apt install software-properties-common
$ sudo add-apt-repository --yes --update ppa:ansible/ansible
$ sudo apt install ansible

Build the Kubernetes cluster using k3s via Ansible²

https://k3s.io/ maintains an Ansible playbook that can set everything up for us.²

It is available here: https://github.com/k3s-io/k3s-ansible[^3]

Download and unzip the repository to the following location, /home/<user>/Downloads/k3s-ansible-master.

Open a command line and navigate to the k3s-ansible-master project directory:

$ cd /Downloads/k3s-ansible-master

Edit the hosts.ini file,

$ nano inventory/sample/hosts.ini

It needs to contain IP addresses for each Raspberry Pi node in our cluster:

Example:

[master]
10.32.25.224

[node]
10.32.25.111
10.32.25.159

[k3s_cluster:children]
master
node

Now edit the group_vars/all.yml file to supply the Ansible username.

$ nano inventory/sample/group_vars/all.yml

Example:

---
k3s_version: v1.17.5+k3s1
ansible_user: <username>
systemd_dir: /etc/systemd/system
master_ip: "{{ hostvars[groups['master'][0]]['ansible_host'] | default(groups['master'][0]) }}"
extra_server_args: ""
extra_agent_args: ""

Remove the config files from the sample directory.

$ mv inventory/sample/* inventory/

Run the following command to start the Ansible playbook:

$ ansible-playbook site.yml -i inventory/hosts.ini

Note: I actually couldn't get this to work using SSH passwordless authentication. I resorted to using the following command:

$ ansible-playbook site.yml -K -i inventory/hosts.ini 

The -K option prompts for the password before the playbook kicks off. Using this method it finished without error.

Install Kubectl on Laptop

Download the latest release with the command:³

$ curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"

Install kubectl:³

$ sudo install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl

Setup Kubectl to administer the cluster

$ scp <user>@master_ip:~/.kube/config ~/.kube/pi-cluster-config

Note: you may need to create the ~/.kube directory if it doesnt already exist.

Set an environment variable to tell kubectl to use our pi-cluster-config file,

$ export KUBECONFIG=~/.kube/pi-cluster-config

Now you can run the following command to see if your pi cluster is up and running:

$ kubectl get nodes

It should return something like this:

NAME        STATUS   ROLES    AGE   VERSION
silverfox   Ready    master   95m   v1.17.5+k3s1
whitefoot   Ready    <none>   95m   v1.17.5+k3s1
cleareyes   Ready    <none>   95m   v1.17.5+k3s1

Acknowledgements

A big shoutout to Jeff Geerling for making the youtube video and tutorial that inspired this article.⁴

Sources

Footnotes

1. Ansible Documentation: Installing Ansibl on Ubuntu ↩ ↩²

2. K3S: Lightweight Kubernetes ↩ ↩²

3. Kubernetes.io: Install Kubectl - Linux ↩ ↩²

4. Video Raspberry Pi Cluster Ep 3 - Installing Kubernetes (K3s) on the Turing Pi
   Publication: Jeff Geerling's Youtube Channel
   Author(s): Jeff Geerling
   Date: May 21, 2020 ↩