I bought some new Raspberry Pi 4s because I have been wanting to play “k8s-at-home” for a while.

And I wanted to use k3s because it was recommended to me and all the k8s twitterati seem to like it.

Setting up the Pis and getting them on my network

First, I set up the Pis. I imaged my micro SD card, using Raspi imager, and using the default image. (32bit raspbian).

I added the empty file ‘ssh’ into the formatted card after Raspi imager had written the raspbian image (just creating a file at the root of the SD card) so that the Pi has ssh enabled on startup.

I did this for both SD cards. I plugged both SD cards into pis, and started the pis up.

Then, after a few mins, I looked up the given Ips that the pis had grabbed via dhcp (I justed used Fing for this, there is probably a clever way to do this on the cli).

I then ssh’d to the Pis.

I also grabbed the mac addresses from the pis, assigned them IPs in my routers DHCP config and assigned those IPs hostnames and FQDNs on my pi.hole.

Finally, I rebooted the pis via sudo reboot now

Putting k3s on there

I ssh’d back to the Pis, and did the extra commands for default raspbian that is required by k3s.

sudo iptables -F
sudo update-alternatives --set iptables /usr/sbin/iptables-legacy
sudo update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy
sudo reboot

Then, I installed k3s with this command:

curl -sfL https://get.k3s.io | sh -s - --write-kubeconfig-mode 644

I found that I needed to add the --write-kubeconfig-mode so that I can kubectl without sudo

Then, I saw this error in my logs.

$ journalctl -u k3s
msg="failed to find memory cgroup, you may need to add \"cgroup_memory=1 cgroup_enable=memory\" to your linux cmdline (/boot/cmdline.txt on a Raspberry 

So I did as the log message asked. I added cgroup_memory=1 cgroup_enable=memory to my /boot/cmdline.txt file.

For reference, that file now looks like:

[email protected]:~ $ cat /boot/cmdline.txt 
console=serial0,115200 console=tty1 root=PARTUUID=db4dbc98-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles cgroup_memory=1 cgroup_enable=memory

…but then I kept getting the same error. After some googling, I looked here and here:

  • https://blog.codybunch.com/2020/07/31/Fixing-cgroup-memory-on-Raspbian-Buster-for-Kernel-54x/
  • https://raspberrypi.stackexchange.com/questions/101790/how-to-revert-from-rpi-update-to-stable-build

And I found this command seemed to give it a kick:

sudo apt-get update; sudo apt-get install --reinstall raspberrypi-bootloader raspberrypi-kernel

and then after another sudo reboot now, it all started working.