Docker Swarm Cluster on Raspberry Pi with Raspbian Stretch

Docker is is on everyone’s lips and now you can also use Docker on the Raspi. But one is not enough, we’ll install a Docker Swarm Cluster. If you’d like to know more about Docker and Swarm see the homepage of Docker Community.

First install a fresh Rasbian Stretch image like explained here:

Raspberry Pi Headless Installation with SSH enabled and WLAN

Update your packages to the newest versions and install some dependencies.

sudo apt-get update && sudo apt-get upgrade
sudo apt-get install apt-transport-https ca-certificates curl gnupg2 software-properties-common

Docker now supports also Debian Stretch (Docker CE Installation Guide)
So you can install Docker easiely with a Helper Script. Download the Script and execute it:

curl -fsSL get.docker.com -o get-docker.sh
sudo sh get-docker.sh

After successful setup, you can add the user ‚pi‘ to the ‚docker‘ group, to directly execute docker commands

sudo usermod -aG docker pi

After a reboot, you can execute the docker commands with your ‚pi‘ login:

docker run hello-world

Initializing a Swarm Cluster

Docker Swarm Documentation

To initialize the Docker Swarm Cluster execute the following command on the first Docker instance:

docker swarm init
Swarm initialized: current node (7nkdamk2m1tdhjzf45gfk5o91) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join \
    --token SWMTKN-1-4ynwgkfmjkj937j7kxlyll7ncucvo8jawijv8lybxourfm2d6n-dcol6t8ulsdl7axyjg2q0moqp \
    192.168.2.58:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

If you get this error…

docker swarm init
Error response from daemon: could not choose an IP address to advertise since this system has multiple addresses on interface wlan0 (fdde:530f:b4e8::f8a and fdde:530f:b4e8:0:ba66:db42:43a1:46eb) - specify one with --advertise-addr

.. you can join one of the IPv6 adresses with –advertise-addr or you can instead disable IPv6 completely:

/etc/sysctl.conf

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

After successfully initializing the cluster, you can get a list of cluster nodes with this command:

docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS
7nkdamk2m1tdhjzf45gfk5o91 *   dockerpi1           Ready               Active              Leader

To add a second instance as worker node, execute the docker swarm join command, like you can see in the output of the docker swarm init command:

docker swarm join \
>     --token SWMTKN-1-4ynwgkfmjkj937j7kxlyll7ncucvo8jawijv8lybxourfm2d6n-dcol6t8ulsdl7axyjg2q0moqp \
>     192.168.2.58:2377
This node joined a swarm as a worker.
 

Docker Compose Installation

Docker Compose Documentation. To Install Docker Compose use this commands:

sudo apt-get install python-pip
sudo pip install docker-compose

docker-compose version
docker-compose version 1.16.1, build 6d1ac219
docker-py version: 2.5.1
CPython version: 2.7.13
OpenSSL version: OpenSSL 1.1.0f  25 May 2017