Docker Clustering on Raspberry Pi

The folks behind Hypriot have made getting Docker up and going on the Raspberry Pi a near on trivial task: Download the image, power it on. They’ve also done the same thing for Docker clustering, here. Which is great, until it isn’t.

That is, their clustering lab has a number of hard requirements around VLAN networking support. If you’ve got a plethora of dumb switches at home, this just wont do!

Have no fear, however, the combination of their image, and their clustering packages seem to be the magical combination.

Hardware bits to have

• Some number of Raspberry Pi’s (I’ve got 3x rPI 2 for this, I think anything b+ will work)
• At least one wifi dongle
• An Ethernet switch

Let’s do this!

This process roughly breaks down like this:

Pull the image down from here. At the time of writing it was “Hector” 0.6.1

Use the Hypriot ‘flash’ script to load your SD card:

```flash –hostname Drekkar –ssid WiFi-Iron –password “$DAVE” /path/to/theimage.img.zip

Do this for each card you have. Once your cards are imaged, plug them in, boot the Pi's, and [find them on the network.](https://github.com/adafruit/Adafruit-Pi-Finder)

For this next trick, I used ssh and broadcast input in iTerm (TMUX works well too), to issue the following commands across all the nodes in my cluster:

sudo apt-get update && sudo apt-get install hypriot-cluster-lab

The prior commands will take a couple of minutes to complete. Once they do, pick a node to be 'master', and direct all input to it (rather than all the nodes). On that node, run the following:

sudo systemctl start cluster-start ```

Again, this will take a few minutes. Once finished, run the prior command on the rest of your cluster nodes. At this point, fetch a coffee, it’ll be a while.

Cool! You’ve now got a Docker Cluster running on Raspberry PI’s

To read more about what the Hypriot group has going on, and some exercises to do with said cluster, check out their git page here.