5.6 KiB
- Pre-requisites
- Step 1 - Prepare boot media for master
- Step 2 - Write the image file to removable media
- Step 3 - Enable ssh at startup
- Step 4 - Enable wifi at startup
This file serves as a complete step by step guide for creating a bare metal raspberry pi kubernetes cluster using k3s from Rancher.
My goal for this build is to replace a server I currently run at home that hosts several workloads via Docker with a scalable k8s cluster.
Additionally in future I would like the cluster to be portable and operate via 3G-5G Cellular network and an array of batteries.
I chose k3s as it incredibly lightweight but still CNCF certified and production grade software that is optimised for resource constraints of raspberry pis.
Pre-requisites
Cluster machines
For this guide I am using three Raspberry Pi 4 4GB machines.
The cluster will have one leader node and two worker nodes. For resiliency puposes in future I will update the cluster to run with two leader nodes.
TODO Migration to high availability control plane
For resiliency purposes in future I will update the cluster and this documentation to support a control plane of more than one machine.
Boot media
This guide requires each Raspberry Pi to have a removable SD card or other removable boot media. I am use three 32GB SD Cards though any USB or SD card at least 8GB in size should work fine.
TODO Migration to network booting
In future it would be preferable for the raspberry pi's to be able to network boot and setup automatically without an SD card.
This is a nice to have that I will pursue at a later date once I have a deployed cluster that allows me to migrate off the current server setup I have deployed.
Step 1 - Prepare boot media for master
Download the latest release
Our first step is to create the bootable SD Card with a minimal install of Raspbian, which is a free operating system based on Debian and is optimised for Raspberry Pi hardware.
Rather than doing an installation and configuration of an operating system image from scratch I found this project on Github which automates the install and configuration process nicely.
echo Downloading latest release zip from github
curl -s https://api.github.com/repos/foodeas/raspberrypi-ua-netinst/releases/latest \
| grep "browser_download_url.*zip" \
| cut -d : -f 2,3 \
| tr -d \" \
| wget -i -
echo Checking file is now present
ls -l | grep *.zip
echo Extracting the zip file
unzip -q -d installer *.zip
ls -l | grep installerDownloading latest release zip from github Checking file is now present -rw-rw-rw- 1 james james 60299545 Aug 12 08:35 raspberrypi-ua-netinst-v2.4.0.zip Extracting the zip file
Apply custom configuration
Our next step after downloading the
Step 2 - Write the image file to removable media
Our next step is to write the downloaded image file to our removable media. This step needs to be repeated for each raspberry pi in the cluster.
Note: As my development environment is based on wsl I need to use
a third party tool to write the image. If you are on a standard linux
distribution you can use the dd utility to write the image.
The image writing utility I use is balena etcher. After downloading the latest version:
- Insert your removable media.
- Select the image file you downloaded earlier.
- Select your removable media and start writing the image.
Step 3 - Enable ssh at startup
As our cluster will be headless, i.e. have no screen keyboard or mouse plugged in we need to ensure ssh is configured from boot so that we can remotely connect.
To do this we just need to add an empty file named ssh to our newly
created sd card
sudo mkdir /media/sdcard
sudo mount /dev/[SDCARD] /media/sdcard -o umask=000sudo touch /media/sdcard/sshStep 4 - Enable wifi at startup
For this guide we are running our cluser wirelessly. To ensure we can access our pi's once they boot we need to ensure they boot with a wifi configuration that will connect to our desired network.
To achieve this we need to set a configuration for the wpa_supplicant application that our raspberry pi's use for managing wireless.
For security reasons I don't store wireless access point details here. Instead they are retrieved at runtime of the code block using the bitwarden command line utility.
export WIRELESS_SSID=`bw get username wifi`
export WIRELESS_PASS=`bw get password wifi`
cat > /media/sdcard/wpa_supplicant.conf << EOF
country=nz
update_config=1
ctrl_interface=/var/run/wpa_supplicant
network={
scan_ssid=1
ssid=$WIRELESS_SSID
psk=$WIRELESS_PASS
}
EOF
After writing the file we will use cat to verify the details.
If all details are correct you can unmount and remove the media.