Ansible playbooks for setting up a Kubernetes Raspberry Pi 3 cluster
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README.md
apt-upgrade-cluster.yml
deployments.yml
hosts.example
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README.md

About

This project is largely based on of a great repository made by Roland Huß: Project31/ansible-kubernetes-openshift-pi3.

Almost everything here (included some parts of this README) is copied from that repository, I changed just a couple of things in order to better handle my custom configurations.

Features

  • From zero to a running cluster with a single Ansible playbook
  • Kubernetes 1.8 with Docker 17
  • WiFi networking and Flannel as CNI
  • Cluster aware storage available out of the box using GlusterFS (replicated on every node)
  • Dashboard and Heapster deployed by default along with Traefik (a reverse proxy that exposes your containers to the outside world)
  • Manual deployments for the Docker registry, MySQL, whoami and Lavagna.

Setup the hardware

Most of the installation is automated by using Ansible. Thanks to Hypriot images a complete headless setup is possible.

  1. Download the latest Hypriots image and store it as hypriot.zip:
curl -L https://github.com/hypriot/image-builder-rpi/releases/download/v1.5.0/hypriotos-rpi-v1.5.0.img.zip
  1. Install Hypriot's flash installer script. Follow the directions on the installation page.

  2. Insert you Micro-SD card in your Desktop computer (via an adapter possibly) and run

flash --hostname n1 --ssid "mysid" --password "secret" hypriotos-rpi-v1.5.0.img.zip

You will be asked to which device to write. Check this carefully, otherwise you could destroy your Desktop OS if selecting the the wrong device. Typically its something like /dev/disk2 on OS X, but depends on the number of hard drives you have. 4. Repeat step 2. to 3. for each Micro SD card. Please adapt the hostname before each round to n2, n3, n4.

Configure the network

It is now time to configure your WLAN router. This of course depends on which router you use. The following instructions are based on a TP-Link TL-WR802N which is quite inexpensive but still absolutely ok for our purposes since it sits very close to the cluster and my notebook anyway.

First of all you need to setup the SSID and password. Use the same credentials with which you have configured your images.

The addresses I have chosen are:

IP Device
192.168.23.1 WLAN Router
192.168.23.181 ... 192.168.23.184 Raspberry Pis

You should be able to SSH into every Pi with user pirate and password hypriot. Internet access from the nodes is mandatory for setting up the nodes with Ansible.

After that you checked every Raspberry you can configure the router using these steps detailed by Sergio Sisternes:

  • Go to DHCP > Client list and take note of the MAC addresses
  • Go to DHCP > Address reservation, and set an static (Reserved) IP address to each Raspberry
  • Go to Quick Setup and configure the router in the hotspot mode so it can connect itself to another router and share Internet with the Raspberries

Ansible playbooks

After this initial setup is done, the next step is to initialize the base system with Ansible. You will need Ansible 2 installed on your desktop (e.g. brew install ansible when running on OS X)

Ansible configuration

  1. Checkout the Ansible playbooks:

     git clone https://github.com/SitoCH/rpi-kubernetes-cluster.git rpi-kubernetes-cluster
     cd rpi-kubernetes-cluster
    
  2. Copy over hosts.example and adapt it to your needs

     cp hosts.example hosts
     vi hosts
    

    There are three groups:

    • pis contains all members of your cluster where one is marked as "master" in the field host_extra. This group will be added to every node in its /etc/hosts. It is important that one host is marked as "master", since the playbooks rely on this host alias for accessing the API server.
    • master IP address of the Master
    • nodes All nodes which are not Master
    • volumes Volumes to create on GlusterFS

Configure the cluster

Run the deployment with the command:

ansible-playbook -k -i hosts setup.yml

Update the nodes

After some time this playbook may be useful to update the nodes:

ansible-playbook -k -i hosts apt-upgrade-cluster.yml

Deploy default applications

Once that the cluster is up and running this playbook will deploy GlusterFS endpoints, Heapster, Dashboard and Traefik:

ansible-playbook -k -i hosts deployments.yml

Traefik

Traefik is a reverse proxy that exposes your containers to the outside world. The management dashboard is available at http://master-node:8080/

Manual deployments

For convenience useful deployments can be found in the directory manual-deployments, please note that you must install the Registry in order to use other manual deployments because the images will be centrally cached.

Registry

This container installs a Docker registry that acts as a pass-trough cache, this way only the first node will download an image from Internet and all the other requests will be served from "inside" the cluster.

kubectl --kubeconfig run/admin.conf create -f manual-deployments/registry/registry.yml

Who am I

Simple container that deploys on 3 nodes a website that prints it's container ID.

Thanks to Traefik you can access it on http://master-node/whoami/

kubectl --kubeconfig run/admin.conf create -f manual-deployments/whoami/whoami.yml

MySQL

MySQL database server with persistent storage.

kubectl --kubeconfig run/admin.conf create -f manual-deployments/mysql/mysql.yml

Lavagna

Lavagna is an open-source issue/project management tool designed for small teams (another open source project of mine made with 2 friends).

kubectl --kubeconfig run/admin.conf create -f manual-deployments/lavagna/lavagna.yml

Acknowledgements

Roland Huß for doing the heavy lifting and creating a project ready to use and easy to deploy.

Lucas Käldström for porting Kubernetes to the Raspberry Pi / ARM.

Sergio Sisternes for providing a great guide on how to setup the WiFi router.