Basic stuff we need :

• Install a operating system in each of the nodes

• Arrange a ssh connection for the nodes

• Prearrange the nodes for K3s installation

Installing the OS and arrange an ssh connection to the nodes

Information and procedure can be followed on the Raspberry Pi official page (link below), simply keep in mind:

• We have to install version 64bits lite (no desktop necessary)

• We have to activate ssh connection

Install OS

Prearrange nodes

After a fight with k3 installation, I found it could be easier if:

• Disable swap in each node

#Disable swap
sudo swapoff -a
#Edit the swap file
sudo nano /etc/dphys-swapfile
# set in the file CONF_SWAPSIZE=0

• Enable cgroup on Raspberry PI nodes.

  Modify file /boot/firmware/cmdline.txt to include the line (be careful it has to be added at the end of the line)

cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory