A tutorial on how to build Kubernetes cluster on Raspberry Pi can be found here. However, there were problems when I follow it, possibly because it is little outdated. The solutions can be found in the comments of that tutorial. This post is a summary of the solution.

Master setup

Change hostname using raspi-config utility.

Set a staic IP address. I use WiFi and didn't set static address. The ip addresses of nodes usually don't change after reboot if the router is the same one used before the reboot.

Install Docker

# remove old version docker
sudo apt-get purge docker-ce docker-ce-cli containerd.io

# export VERSION=17.03 && curl -sSL get.docker.com | sh && \
# sudo usermod pi -aG docker

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

Turn off swap:

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

Edit /boot/cmdline.txt. Add the following line to the end of the line, but don't create any new lines:

cgroup_enable=cpuset cgroup_enable=memory cgroup_memory=1

Reboot

sudo reboot

Install kubectl and kubeadm

# the following command not working after updating the system
# curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add - && \
# echo "deb https://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 kubelet=1.9.7-00 kubectl=1.9.7-00 kubeadm=1.9.7-00  kubernetes-cni=0.6.0-00  --allow-downgrades

# the following commands work
 $ 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

Initialize your master node

sudo kubeadm init --token-ttl=0  
# --apiserver-advertise-address=192.168.0.100 --ignore-preflight-errors=ALL

Install weave 1.6

# 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')"

After the init is complete run the snippet:

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

The above command outputs a toekn which will be used for nodes to join the master. save the token somewhere. The token will be expired after 24 hours.

Join other nodes:

Change hostname using raspi-config

Join the cluster:

$ sudo kubeadm join --token 1fd0d8.67e7083ed7ec08f3 192.168.0.27:6443

Check the nodes on the cluster:

$ kubectl get nodes