Lab with Kubernetes and Traefik on Raspberry

Edmund Haselwanter | 22.04.2017 Cloud Native

Install then base OS

install the flash tool GitHub - hypriot/flash: Command line script to flash SD card images of any kind

1curl -O https://raw.githubusercontent.com/hypriot/flash/master/$(uname -s)/flash
2chmod +x flash
3sudo mv flash /usr/local/bin/flash

if you want a progress bar install pv and for downloading it is good to have wget

1brew install pv wget

get a version from Releases hypriot/image-builder-rpi GitHub

1wget https://github.com/hypriot/image-builder-rpi/releases/download/v1.2.1/hypriotos-rpi-v1.2.1.img.zip

1flash --hostname node01 hypriotos-rpi-v1.2.1.img.zip
2flash --hostname node02 hypriotos-rpi-v1.2.1.img.zip
3flash --hostname node03 hypriotos-rpi-v1.2.1.img.zip

1ssh pirate@black-pearl.local # password "hypriot"

You should ensure that the IP address of your devices do not change. Either configure DHCP to give out the same IP all the time, or edit /etc/network/interfaces.d/eth0, and change it from DHCP:

1iface eth0 inet dhcp

To a static IP config:

1iface eth0 inet static
2address your-static-ip
3gateway your-gateway-ip
4#google dns servers
5domain_name_servers=8.8.8.8, 8.8.4.4

Upgrade OS

Releases · hypriot/image-builder-rpi · GitHub

1$ sudo apt-get update
2$ sudo apt-get upgrade -y
3$ sudo reboot

Fix machine-id

/etc/machine-id the same on every installation · Issue #167 · hypriot/image-builder-rpi · GitHub

Run

1dbus-uuidgen > /etc/machine-id

Change Init

If you want to change e.g. hostname or do other things on init. The device-init tool reads the file /boot/device-init.yaml to initialize several settings while booting your device. GitHub - hypriot/device-init: Initialize a device on boot with user defined configuration

Install Kubernetes

Follow Installing Kubernetes on Linux with kubeadm Kubernetes

Basically (April/2017) do:

Become root on all your machines and run:

1apt-get update && apt-get install -y apt-transport-https
2curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
3cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
4deb http://apt.kubernetes.io/ kubernetes-xenial main
5EOF
6apt-get update
7# Install docker if you don't have it already.
8apt-get install -y docker-engine
9apt-get install -y kubelet kubeadm kubectl kubernetes-cni

Initialize the master:

1kubeadm init

Which should finish with something like:

 1Your Kubernetes master has initialized successfully!
 2
 3To start using your cluster, you need to run (as a regular user):
 4
 5  sudo cp /etc/kubernetes/admin.conf $HOME/
 6  sudo chown $(id -u):$(id -g) $HOME/admin.conf
 7  export KUBECONFIG=$HOME/admin.conf
 8
 9You should now deploy a pod network to the cluster.
10Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
11  http://kubernetes.io/docs/admin/addons/
12
13You can now join any number of machines by running the following on each node
14as root:
15
16  kubeadm join --token <token> <master-ip>:<master-port>

install a pod network. You have to choose a plugin for that. Integrating Kubernetes via the Addon - Weaveworks

1export KUBECONFIG=$HOME/admin.conf
2kubectl apply -f https://git.io/weave-kube-1.6

now join the remaining nodes

1$node2: kubeadm join --token <token> <master-ip>:<master-port>
2$node3: kubeadm join --token <token> <master-ip>:<master-port>

Test the cluster

Install a tiny service

1kubectl run hypriot --image=hypriot/rpi-busybox-httpd --replicas=3 --port=80

Expose the port to access it from now of your nodes

1kubectl expose deployment hypriot --port 80

Access the endpoints

1$ kubectl get endpoints hypriot
2NAME      ENDPOINTS                                AGE
3hypriot   10.32.0.3:80,10.32.0.4:80,10.40.0.1:80   1h

And test it with curl

 1HypriotOS/armv7: pirate@raspi-01 in ~
 2$ curl 10.32.0.3
 3<html>
 4<head><title>Pi armed with Docker by Hypriot</title>
 5  <body style="width: 100%; background-color: black;">
 6    <div id="main" style="margin: 100px auto 0 auto; width: 800px;">
 7      <img src="pi_armed_with_docker.webp" alt="pi armed with docker" style="width: 800px">
 8    </div>
 9  </body>
10</html>

Access it from the Outside - Ingress with Traefik

A good explanation on Kubernetes Ingress can be found here: Kubernetes Ingress – Jay Gorrell – Medium Since we use Kubernetes >= 1.6 with RBAC we need to do a little bit more then in the past. A starting point can be found here: https://doc.traefik.io/traefik/v1.7/user-guide/kubernetes/#role-based-access-control-configuration-kubernetes-16-only

Since we run Træfik on Kubernetes we must change the example to use a arm image.

1wget https://raw.githubusercontent.com/traefik/traefik/v1.7/examples/k8s/traefik-rbac.yaml

Find the line

1   - image: traefik

And change it to

1   - image: hypriot/rpi-traefik

apply the config

1kubectl apply -f traefik-with-rbac.yaml

And add an Ingress object:

 1$ cat > hypriot-ingress.yaml <<EOF
 2apiVersion: extensions/v1beta1
 3kind: Ingress
 4metadata:
 5  name: hypriot
 6spec:
 7  rules:
 8  - http:
 9      paths:
10      - path: /
11        backend:
12          serviceName: hypriot
13          servicePort: 80
14EOF

Now you should be able to access the hypriot deployment on the node were the loadbalancer got deployed

Deploy Kubernetes UI

Super simple:

1curl -sSL https://rawgit.com/kubernetes/dashboard/master/src/deploy/kubernetes-dashboard.yaml | sed "s/amd64/arm/g" | kubectl create -f -

Wait a little bit and run

1kubectl -n kube-system get service kubernetes-dashboard -o template --template="{{"{{ (index .spec.ports 0).nodePort "}}}}" | xargs echo

This will output the port were you can reach the k8s dashboard

Using Hostname Ingress with Traefik

A good writeup can be found here: Kubernetes - Træfɪk

 1$ cat > traefic-ui.yml <<EOF
 2apiVersion: v1
 3kind: Service
 4metadata:
 5  name: traefik-web-ui
 6  namespace: kube-system
 7spec:
 8  selector:
 9    k8s-app: traefik-ingress-lb
10  ports:
11  - port: 80
12    targetPort: 8081
13---
14apiVersion: extensions/v1beta1
15kind: Ingress
16metadata:
17  name: traefik-web-ui
18  namespace: kube-system
19spec:
20  rules:
21  - host: traefik-ui.example.com
22    http:
23      paths:
24      - backend:
25          serviceName: traefik-web-ui
26          servicePort: 80
27EOF

1kubectl apply -f traefic-ui.yml

Now either use your DNS server settings or an /etc/hosts setting to access the traffic UI

1echo "10.20.0.5 traefik-ui.example.com" | sudo tee -a /etc/hosts

1$ kubectl --namespace=kube-system get ingress
2NAME             HOSTS                               ADDRESS   PORTS     AGE
3traefik-web-ui   traefik-ui.example.com             80        1h

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