Installation

From the terminal on a Raspberry Pi, run the following.

# Downloads installation shell script and pipes it into the sh command
curl -sSL https://get.docker.com | sh
# Adds pi to the docker group so the user can run
sudo usermod -aG docker pi

From here we can either reboot or run systemctl start docker.service to start up Docker. To test it is working, try docker info, then docker version.

Once you know that Docker is running, let’s try a few things in order of sophistication. docker run hello-world will run a container based on an image called hello-world. docker run -it ubuntu bash takes it up a notch: now we have an ubuntu bash container running in interactive mode in the terminal.

To make it even more useful, we ought to have access to persistent storage. Let’s modify the command to include a mount volume.

docker run -it -v /home:/home ubuntu bash

The -v flag tells Docker to attach a volume; the following argument contains the information on what locations should be used, of the form from_volume:to_volume. The location on your machine is the from_volume and the location on your container is the to_volume. In our example, anything you create in the home folder within the container will persist in the home folder of your Raspberry Pi after you close the container. The easiest way to test this is to type touch myfile in the interactive terminal in the container, and watch the same file appear in your home folder.

Build an R container

Building a base R container is as simple as writing the code below to a file called Dockerfile. We use an arm32 ubuntu image as a base, from which we set an environment variable to force the terminal to be non-interactive. This is because when r-base is installed it waits for user input when setting parameters, hanging the container build. By setting the installation to be non-interactive we accept all the defaults, including timezone. Be mindful of this when handling datetimes!

FROM arm32v7/ubuntu
ENV DEBIAN_FRONTEND=noninteractive
RUN apt update && apt install r-base -y

Once the Dockerfile is created you run it by typing docker build -t armr in the same folder in the terminal. Docker then builds an image with the tag armr. It builds by starting with the base image, setting the environment variable and adding a layer that comprises the result from the RUN command.

In fact, you can see all the layers that are built into any image by running docker history <image_name> in the terminal.