PI4 k3s install server currently unable to handle the request - kubernetes

Question

I'm trying to install and run a single-node lightweight kubernetes cluster, to play around with on my Raspberry pi4, of which I found k3s. However, from what I've read or seen, I'm probably missing something, but haven't found reference to the exact problem I'm getting (testing with simple kubectl command after installation):
$ kubectl get nodes
Error from server (ServiceUnavailable): the server is currently unable to handle the request
The installations that I've referenced:
Turing Pis, multi-node cluster
-> The part of knowing and using Ansible currently seems like bit of a overkill)
Pi setup & k3s install -> Good tutorial, but not having similar config responses?
$ sudo k3s server
INFO[2020-09-30T06:58:13.488363192+01:00] Starting k3s v1.18.9+k3s1 (630bebf9)
INFO[2020-09-30T06:58:13.489450500+01:00] Cluster bootstrap already complete
FATA[2020-09-30T06:58:13.535582640+01:00] starting kubernetes: preparing server: start cluster and https: listen tcp :6443: bind: address already in use
Presumed that this isn't necessary anymore then, based on the newer installation version.
complete k3s 101 youtube -> Still not magically working, as shown.
So if anyone is able to please help me, or guide me in a direction to better debug and display the problem so that I understand and can fix the problem.
Feedback from the installation didn't display that anything went wrong:
$ sudo curl -sfL https://get.k3s.io | INSTALL_K3S_EXEC="--write-kubeconfig-mode 664" sh -
[INFO] Finding release for channel stable
[INFO] Using v1.18.9+k3s1 as release
[INFO] Downloading hash https://github.com/rancher/k3s/releases/download/v1.18.9+k3s1/sha256sum-arm.txt
[INFO] Downloading binary https://github.com/rancher/k3s/releases/download/v1.18.9+k3s1/k3s-armhf
[INFO] Verifying binary download
[INFO] Installing k3s to /usr/local/bin/k3s
[INFO] Creating /usr/local/bin/kubectl symlink to k3s
[INFO] Creating /usr/local/bin/crictl symlink to k3s
[INFO] Creating /usr/local/bin/ctr symlink to k3s
[INFO] Creating killall script /usr/local/bin/k3s-killall.sh
[INFO] Creating uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO] env: Creating environment file /etc/systemd/system/k3s.service.env
[INFO] systemd: Creating service file /etc/systemd/system/k3s.service
[INFO] systemd: Enabling k3s unit
Created symlink /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
[INFO] systemd: Starting k3s
After that, trying commands:
$ k3s --version
k3s version v1.18.9+k3s1 (630bebf9)
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.9+k3s1", GitCommit:"630bebf94b9dce6b8cd3d402644ed023b3af8f90", GitTreeState:"clean", BuildDate:"2020-09-17T19:04:57Z", GoVersion:"go1.13.15", Compiler:"gc", Platform:"linux/arm"}
Error from server (ServiceUnavailable): the server is currently unable to handle the request
$ sudo kubectl get nodes
Error from server (ServiceUnavailable): the server is currently unable to handle the request
$ sudo k3s kubectl get nodes
The connection to the server 127.0.0.1:6443 was refused - did you specify the right host or port?
And looking with htop, definitely 'something' is happening with k3s servers:
Not sure if anything is missing, or must be changed to hosts, for k3s server + agent on device:
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
127.0.1.1 raspberrypi
... No clue what to debug further??

Answer 1

After learning a bit more of the installation process, by watching this video (k3s install on Pi4 - live walkthrough), I noticed that k3s runs as a service on raspbian.
meaning you're able to:
# see all listed services, to find the name of the running k3s service
$ systemctl --type=service
# service name ironically being 'k3s', and being able to follow the logs for service
$ journalctl -u k3s -f
However, looking in '/boot/cmdline.txt', these cgroup values where in the file, but after a endline-character, which prohibited the k3s service sufficiently reading from the file. File content required to be:
$ sudo cat /boot/cmdline.txt
console=serial0,115200 console=tty1 root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait cgroup_enable=1 cgroup_memory=1 cgroup_enable=memory
With that done, I checked journalctl again for the logs, and noticed significantly other logs, regarding pod's containers etc. Master node being functional!:
$ sudo kubectl get nodes
NAME STATUS ROLES AGE VERSION
raspberrypi Ready master 3m52s v1.18.9+k3s1
If this still doesn't work, I also saw a recent blog post regarding the same issue (due to raspbian kernal update), where fix is also suggested -> post