Use K3S a lightweight Kubernetes variant well suited to the Raspberry PI https://github.com/rancher/k3s
K8S has a much larger memory requirement (2Gb) hence opting for K3S.
For the Container runtime containerd is a production grade runtime that has a much smaller foot print than Docker and a much smaller memory requirement
The Raspberry Pi Model 3 A+ has built in wifi. You dont need a keyboard, monitor or ethernet cable, headless setup over SSH is a straight forward process
Download Raspbian Buster Lite from here https://www.raspberrypi.org/downloads/raspbian/ and load onto an SD card
creat an empty file called ssh in the boot folder /rootfs
edit /etc/hosts and set the hostname
::1 localhost ip6-localhost ip6-loopback
127.0.1.1 <your host name>
also set the above hostname in in /etc/hostname
Disable swap in file /etc/dphys-swapfile
edit /etc/wpa_supplicant/wpa_supplicant.conf and add wifi details
ssid="<your networks ssid>"
turn on the pi and SSH in.
As a first step change the password for ui pi from the default raspberry :-
Configure each Raspberry Pi Node.
curl -sfL https://get.k3s.io | sh -
On the master node verify K3S s running and is connected to each node