More is always better: building a cluster with Pies

Raspberry Pi 2

So you have written the uber-pro-web-application with a bazillion of active users. But your requests start to get out of hand and the Raspberry Pi under your desk can’t handle all the pressure on its own. Finally, the time for rapid expansion has come!

If you have already containerized your application, the step towards clustering your software isn’t that hard. In this post, we want to shed some light on management tools you can use to handle a cluster of Docker nodes.

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More docker = more power? – Part 3: Setting up the loadbalancer

To benefit from using a loadbalancer we need several machines to distribute the traffic on, evidently.
Thanks to Docker we simply run

docker run -d -p 81:80 testwebsite:1 

to get a second machine. This time the container port of the webserver is mapped to port 81. If you now visit <IP OF YOUR VM>:81 you should see your test website.
You can have as many machines as you want to. Simply pay attention to the ports.
Of course we don’t want to write this command manually each time when we want to create a new container. Especially not when we want about 100 new containers. That’s why we wrote a small bash script, which does the job for us.

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More docker = more power? – Part 2: Setting up Nginx and Docker

This is Part 2 of a series of posts. You can find Part 1 here:

In the first part of this series we have set up two VirtualBox machines. One functions as the load balancer and the other will house our services. As the next step we want to install docker on the service VM. To do that enter the following commands in the bash:

$ wget -qO- | sh
$ sudo gpasswd -a <username> docker
$ newgrp docker

This downloads and installs Docker, adds your user to the docker user group and logs you into this new group to allow you to create and run containers.

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More docker = more power? – Part 1: Setting up VirtualBox

This series of blogposts will focus on the effects on response times when performing different tasks running on a variable number of docker containers in a virtual machine.
What will be the performance differences running a small or large number of containers on the same machine? These posts will function as a step-by-step tutorial, enabling everyone to reproduce our studies.
In production one of the most scaled services are webservers. Therefore, we want to focus on stress testing a self hosted website that is being load balanced and running in a varying number of Docker containers.

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Docker- dive into its foundations

Docker has gained a lot of attention over the past several years. But not only because of its cool logo or it being the top buzzword of managers, but also because of its useful features. We talked about Docker quite a bit without really understanding why it’s so great to use. So we decided to take a closer look on how Docker actually works.

In this article, we want to shed some light on a few technologies used by Docker enabling it to be so lightweight and fast in startup compared to “traditional” virtual machines (VMs). Docker itself serves us as an example, you could replace it with any other container technology, for example LXC.

Reading this article requires some profound knowledge of virtualization. Terms like “guest system” or “hypervisor” should ring a bell. Also you should have heard of an operating system called Linux (it is probably running on your smartphone and you are waiting for an update).

So let’s go!

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