Workshop

In this workshop we'll set up a raspberry pi cluster and run some configuration scenarios to familiarize you with kubernetes cluster administration.

Prerequsities

The raspberry pi cluster is connected to the internet and is accessible from your laptop or workstation.

Basic knowledge of linux and SSH is expected

Each team has been given their own raspberry pi cluster with unique IP addresses and node names. Each raspberrypi has been preconfigured to run kubernetes.

Tools

Linux shell: with ssh support and the kubernetes-CLI (kubectl) installed.

Node: any version of node.js or your favourite tool to generate http load

Creating a Kubernetes cluster

Pi configuration

On each pi, change the name, disable swap, cgroups and enable ssh

1. Change the name

echo "raspberrypi4" | sudo tee /etc/hostname
# TODO remove original hostname on the last line
echo "127.0.1.1	raspberrypi4" | sudo tee -a /etc/hosts

1. Disable swap

sudo dphys-swapfile swapoff &&
sudo dphys-swapfile uninstall &&
sudo systemctl disable dphys-swapfile

1. Enable cgroups

echo " cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory" >> /boot/cmdline.txt

1. enable ssh

touch /boot/ssh

1. update

sudo rpi-update

1. iptables legacy

sudo update-alternatives --set iptables /usr/sbin/iptables-legacy
sudo sysctl net.bridge.bridge-nf-call-iptables=1

1. reboot

sudo reboot

Install docker and kubernetes

1. Install Docker

   Kubernetes is an container orchestrator that runs on docker.

   Run the following command to install docker comminuty edition on the node:

   curl -sSL get.docker.com | sh

2. Install kubeadm

   Kubernetes is managed through APIs on both master and worker nodes. kubeadm is used for cluster administration, such as joining a cluster.

   Install the kubeadm tool on your node:

   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

This step is based on the following source.

1. pull kubeadm images

sudo kubeadm config images pull

Find the hosts

1. get the network range

ifconfig

1. scan the network for hosts:

IP addresses should be used when joining the cluster since we're using mDNS and not a proper DNS server:

sudo nmap -sn 192.168.1.0/24

Nmap scan report for 192.168.0.100
Host is up (0.00058s latency).
MAC Address: DC:A6:32:12:C1:68 (Raspberry Pi Trading)
Nmap scan report for 192.168.0.101
Host is up (0.00057s latency).
MAC Address: DC:A6:32:12:C1:A7 (Raspberry Pi Trading)
Nmap scan report for 192.168.0.103
Host is up (0.00057s latency).
MAC Address: DC:A6:32:12:C1:A1 (Raspberry Pi Trading)
Nmap scan report for 192.168.0.105
Host is up (0.00064s latency).
MAC Address: DC:A6:32:5F:B6:06 (Raspberry Pi Trading)
Nmap scan report for 192.168.0.106
Host is up (0.00063s latency).
MAC Address: DC:A6:32:12:C2:C4 (Raspberry Pi Trading)

https://medium.com/developingnodes/setting-up-kubernetes-cluster-on-raspberry-pi-15cc44f404b5

Initialize the master

Execute the follwing command on the master:

sudo kubeadm init --pod-network-cidr=10.244.0.0/16

copy the kubeconfig file

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

Join the nodes

Execute the command output from the master on each worker node to join the master:

sudo kubeadm join 192.168.1.101:6443 --token h6wf20.u2db8cdxr83hrloq \
    --discovery-token-ca-cert-hash sha256:ffaf845205a3cca38859c900861bd01e28353ec93009cd35cb405e717e1b3c6b

Flannel

Flannel is a simple and easy way to configure a layer 3 network fabric designed for Kubernetes.

    kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
    kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/k8s-manifests/kube-flannel-rbac.yml

Wait until the coros pods are ready:

kubectl wait --for=condition=Ready pod -l k8s-app==kube-dns -n kube-system

Blinkt

1. Grant access to the blinkt pods to get pod information from the kubernetes API:

   kubectl create -f https://raw.githubusercontent.com/apprenda/blinkt-k8s-controller/master/kubernetes/blinkt-k8s-controller-rbac.yaml
   kubectl create -f https://raw.githubusercontent.com/jonaseck2/raspberry-cluster/master/blinkt-k8s-controller-ds.yaml

2. Label the nodes to start the daemonset pods on the node

   kubectl label node --all deviceType=blinkt

3. Untaint the master to schedule a pod there as well

   kubectl taint nodes --all node-role.kubernetes.io/master-

Whack a pod

game-api

1. place the kubeconfig file in the api cluster folder

scp pi@raspberrypi0.local:~/.kube/config game-api/clusters/raspberrypi0.yaml

1. npm install and start

cd game-api
npm install
npm start

start a new terminal

game-ui

1. npm install and start

npm install
npm start

1. Add some moles

kubectl apply -f https://raw.githubusercontent.com/jonaseck2/raspberry-cluster/master/deployment.yaml

kubectl scale deployment.v1.apps/lmw-leaf --replicas=25