K8s on Raspbian

k8s-pi.md

This guide has moved to a GitHub repository to enable collaboration and community input via pull-requests.

https://github.com/alexellis/k8s-on-raspbian

Alex

prep.sh

#!/bin/sh

# This installs the base instructions up to the point of joining / creating a cluster

curl -sSL get.docker.com | sh && \
  sudo usermod pi -aG docker

sudo dphys-swapfile swapoff && \
  sudo dphys-swapfile uninstall && \
  sudo update-rc.d dphys-swapfile remove

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add - && \
  echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list && \
  sudo apt-get update -q && \
  sudo apt-get install -qy kubeadm
  
echo Adding " cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory" to /boot/cmdline.txt

sudo cp /boot/cmdline.txt /boot/cmdline_backup.txt
orig="$(head -n1 /boot/cmdline.txt) cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory"
echo $orig | sudo tee /boot/cmdline.txt

echo Please reboot

quick.md

Use this to setup quickly

# curl -sL \
 https://gist.githubusercontent.com/alexellis/fdbc90de7691a1b9edb545c17da2d975/raw/b04f1e9250c61a8ff554bfe3475b6dd050062484/prep.sh \
 | sudo sh

Install Kubernetes 1.13.1 on Raspberry Pi Cluster

This comment combines the knowledge of this gist and the many comments above plus the workings of https://github.com/aaronkjones/rpi-k8s-node-prep

Download Raspbian Stretch Lite (2018-11-13 4.14 kernel), flash to sd cards for your cluster (in my case 5 cards).Once flashed and BEFORE you boot the pis, set up the networking by mounting the sd card (you can of course just boot the Pis and setup networking on each machine, my personal preference is to do this in advance):

Turn on ssh: sudo touch <boot partition mount point>/ssh

Enable C-Groups: sudo vi <boot partition mount point>/cmdline.txt

dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=PARTUUID=7ee80803-02 rootfstype=ext4 elevator=deadline fsck.repair=yes group_enable=cpuset cgroup_memory=1 cgroup_enable=memory rootwait quiet init=/usr/lib/raspi-config/init_resize.sh

I'm using wired networking on a 192.168.2.xx subnet so setup the host entries: sudo vi <rootfs partition mount point>/etc/hosts

 	...add to bottom of file...
	192.168.2.31       node01
	192.168.2.32       node02
	192.168.2.33       node03
	192.168.2.34       node04
	192.168.2.35       node05

sudo vi <rootfs partition mount point>/etc/dhcpcd.conf

	...add to bottom of file...
    interface eth0
	static ip_address=192.168.2.XX/24   <--- change XX = 31,32,33,34,35
	static routers=192.168.2.1
	static domain_name_servers=192.168.2.1

Unmount the sd card, then in turn mount the other 4 sd cards repeating the steps above changing the ip address. Once you have setup all 5 sdcards put them into the pis and power on the cluster. SSH to each in turn and complete the configuration and install the software with the below steps.

ssh pi@192.168.2.XX

sudo -i
hostnamectl set-hostname nodeXX <- change to node01/02/03/04/05 as appropriate
apt-get update
apt-get upgrade -y

curl -s https://download.docker.com/linux/raspbian/gpg | sudo apt-key add -
echo "deb [arch=armhf] https://download.docker.com/linux/raspbian stretch edge" | sudo tee /etc/apt/sources.list.d/socker.list
apt-get update -q
apt-get install -y docker-ce=18.06.0~ce~3-0~raspbian --allow-downgrades
echo "docker-ce hold" | sudo dpkg --set-selections
usermod pi -aG docker

dphys-swapfile swapoff
dphys-swapfile uninstall
update-rc.d dphys-swapfile remove

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
apt-get update -q
apt-get install -y kubeadm=1.13.1-00 kubectl=1.13.1-00 kubelet=1.13.1-00

reboot

Setup master node01

ssh pi@192.168.2.31

sudo kubeadm init --token-ttl=0 --apiserver-advertise-address=192.168.2.31 --kubernetes-version v1.13.1

Save the join token and token hash, it will be needed in "Setup slave nodes02-05"

Make local config for pi user, so login as pi on node01

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Check it's working (except the dns pods wont be ready)

kubectl get pods --all-namespaces

Setup kubernetes ovverlay networking

kubectl apply -f https://git.io/weave-kube-1.6
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"

Setup slave nodes02-05

Join the cluster using the join token and token hash when you ran kubeadm on node01

sudo kubeadm join 192.168.2.31:6443 --token xxxxxxxxxxxxxxxxxxxxxxxx --discovery-token-ca-cert-hash sha256:yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy

Back on the master node01 check the nodes have joined the cluster and that pods are running:

kubectl get nodes
kubectl get pods --all-namespaces

Deploy dashboard

Deploy the tls disabled version of the dashboard

echo -n 'apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard
  labels:
    k8s-app: kubernetes-dashboard
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: kubernetes-dashboard
  namespace: kube-system' | kubectl apply -f -

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/alternative/kubernetes-dashboard-arm.yaml

To access the dashboard start the proxy on node01:
kubectl proxy --address 0.0.0.0 --accept-hosts '.*'

Then from your pc point your browser at:
http://192.168.2.31:8001/api/v1/namespaces/kube-system/services/http:kubernetes-dashboard:/proxy/

@andyburgin I followed your instructions, but I can't get the master node running...

The kubeadm init [...] did not finish:

[...]
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[kubelet-check] Initial timeout of 40s passed.

Unfortunately, an error has occurred:
        timed out waiting for the condition

This error is likely caused by:
        - The kubelet is not running
        - The kubelet is unhealthy due to a misconfiguration of the node in some way (required cgroups disabled)

If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
        - 'systemctl status kubelet'
        - 'journalctl -xeu kubelet'

Additionally, a control plane component may have crashed or exited when started by the container runtime.
To troubleshoot, list all containers using your preferred container runtimes CLI, e.g. docker.
Here is one example how you may list all Kubernetes containers running in docker:
        - 'docker ps -a | grep kube | grep -v pause'
        Once you have found the failing container, you can inspect its logs with:
        - 'docker logs CONTAINERID'
error execution phase wait-control-plane: couldn't initialize a Kubernetes cluster

I waited for some time until all pod were "Running":

$ kubectl get pods --all-namespaces

NAMESPACE     NAME                                 READY   STATUS    RESTARTS   AGE
kube-system   etcd-msh-master                      1/1     Running   0          105s
kube-system   kube-apiserver-msh-master            1/1     Running   5          107s
kube-system   kube-controller-manager-msh-master   1/1     Running   0          115s
kube-system   kube-scheduler-msh-master            1/1     Running   0          76s

_{(is it possible that kube-dns and kube-proxy are missing?)}

Then I applied the two weave-net files you mentioned:

kubectl apply -f https://git.io/weave-kube-1.6
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"

But the weave-net pod will not become "Running"...

ERROR: logging before flag.Parse: E0120 16:25:32.259195   11085 reflector.go:205] github.com/weaveworks/weave/prog/weave-npc/main.go:319: Failed to list *v1.Pod: Get https://10.96.0.1:443/api/v1/pods?limit=500&resourceVersion=0: dial tcp 10.96.0.1:443: i/o timeout
ERROR: logging before flag.Parse: E0120 16:25:32.267598   11085 reflector.go:205] github.com/weaveworks/weave/prog/weave-npc/main.go:320: Failed to list *v1.NetworkPolicy: Get https://10.96.0.1:443/apis/networking.k8s.io/v1/networkpolicies?limit=500&resourceVersion=0: dial tcp 10.96.0.1:443: i/o timeout
ERROR: logging before flag.Parse: E0120 16:25:32.274948   11085 reflector.go:205] github.com/weaveworks/weave/prog/weave-npc/main.go:318: Failed to list *v1.Namespace: Get https://10.96.0.1:443/api/v1/namespaces?limit=500&resourceVersion=0: dial tcp 10.96.0.1:443: i/o timeout

10.96.0.1 seems to be the kubernetes service IP:

$ kubectl get services
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   17m

Oooookayy... I finally managed to get it working \o/

I wrote a small bash script that checks for /etc/kubernetes/manifests/kube-apiserver.yaml to update failureThreshold (new value: 100) and initialDelaySeconds (new value: 1080) as soon as the file exists. The new values are much bigger than they need to be, but they allowed my to get my master node up and running! Whenever I tried to change these values this by hand, the kubeadm init ... command failed.

I just set up a working cluster but couldn't get the master running on an RPI 2. Moved SD card over to a RPI 3 and then kubeadm init ran just fine. The worker node seem to run just fine on the RPI 2.

Wondering if anyone has gotten helm/tiller working in this configuration?

@rnbwkat I got it working but I had to specify a different tiller image, one which was compatible with ARM. The command I used was:

helm init --service-account tiller --tiler-image=jessestuart/tiller:v2.9.0

@janpieper. I’ve run into the “node not found”. looking through all the comments I was going to follow the save steps you did. I wonder what versions of k8s and docker you’ve installed

I tried to setup the cluster following the steps described but still didn't get a succesful kubeadm init. I tried different versions of k8s and docker. Is there somebody who has the steps to get 1.13-3 working with 18.09.0

@janpieper can you share the script?

@janpieper steps worked up until the point everyone mentioned, and rather than the script that polls and zaps the config, I found you can do the same (after the initial failure) by running these commands (lifted from this issue kubernetes/kubeadm#1380)

sudo kubeadm reset
sudo kubeadm init phase certs all
sudo kubeadm init phase kubeconfig all
sudo kubeadm init phase control-plane all --pod-network-cidr 10.244.0.0/16
sudo sed -i 's/initialDelaySeconds: [0-9][0-9]/initialDelaySeconds: 240/g' /etc/kubernetes/manifests/kube-apiserver.yaml
sudo sed -i 's/failureThreshold: [0-9]/failureThreshold: 18/g'             /etc/kubernetes/manifests/kube-apiserver.yaml
sudo sed -i 's/timeoutSeconds: [0-9][0-9]/timeoutSeconds: 20/g'            /etc/kubernetes/manifests/kube-apiserver.yaml
sudo kubeadm init --v=1 --skip-phases=certs,kubeconfig,control-plane --ignore-preflight-errors=all --pod-network-cidr 10.244.0.0/16

Then I installed flannel.

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.11.0/Documentation/kube-flannel.yml

Something that threw me off was the shell demo that Kubernetes provides works fine (kubectl apply -f https://k8s.io/examples/application/shell-demo.yaml) docs here:
https://kubernetes.io/docs/tasks/debug-application-cluster/get-shell-running-container/

But it fails when doing a deployment of nginx from their example here:
https://kubernetes.io/docs/tasks/run-application/run-stateless-application-deployment/

Turns out the nginx image isn't compatible with ARM, once I changed the image to a pi supported image (tobi312/rpi-nginx
) it worked fine! Thanks to everyone here, I finally got my pi cluster going.