Setting up your Embedded Device¶

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[!NOTE] This guide is applicable to many embedded devices such as Raspberry Pi. This guide assumes you have a fresh install of Raspberry Pi OS Lite or Ubuntu Server (e.g. 22.04) and that you have successfully ssh-ed into your device.

Setting up your device for Python developemnet¶

We are going to use pyenv to manage different Python versions and to create an environment. First, we need to install some system dependencies

sudo apt-get update
# Install python deps relevant for this and other examples
sudo apt-get install build-essential zlib1g-dev libssl-dev \
                libsqlite3-dev libreadline-dev libbz2-dev \
                git libffi-dev liblzma-dev libsndfile1 -y

# Install some good to have
sudo apt-get install htop tmux -y

# Add mouse support for tmux
echo "set-option -g mouse on" >> ~/.tmux.conf

It is recommended to work on virtual environments instead of in the global Python environment. Let’s install pyenv with the virtualenv plugin.

Install pyenv and virtualenv plugin¶

git clone https://github.com/pyenv/pyenv.git ~/.pyenv
echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
echo 'command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(pyenv init -)"' >> ~/.bashrc

# Now reload .bashrc
source ~/.bashrc

# Install pyenv virtual env plugin
git clone https://github.com/pyenv/pyenv-virtualenv.git $(pyenv root)/plugins/pyenv-virtualenv
# Restart your shell
exec "$SHELL"

Create a Python environment and activate it¶

[!TIP] If you are using a Raspberry Pi Zero 2 or another embedded device with a small amount of RAM (e.g. <1GB), you probably need to extend the size of the SWAP partition. See the guide at the end of this readme.

Now all is ready to create a virtualenvironment. But first, let’s install a recent version of Python:

# Install python 3.10+
pyenv install 3.10.14

# Then create a virtual environment
pyenv virtualenv 3.10.14 my-env

Finally, activate your environment and install the dependencies for your project:

# Activate your environment
pyenv activate my-env

# Then, install flower
pip install flwr

# Install any other dependency needed for your device
# Likely your embedded device will run a Flower SuperNode
# This means you'll likely want to install dependencies that
# your Flower `ClientApp` needs.

pip install <your-clientapp-dependencies>

Extening SWAP for RPi Zero 2¶

[!NOTE] This mini-guide is useful if your RPi Zero 2 cannot complete installing some packages (e.g. TensorFlow or even Python) or do some processing due to its limited RAM.

A workaround is to create a swap disk partition (non-existant by default) so the OS can offload some elements to disk. I followed the steps described in this blogpost that I copy below. You can follow these steps if you often see your RPi Zero running out of memory:

# Let's create a 1GB swap partition
sudo fallocate -l 1G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
# Enable swap
sudo swapon /swapfile # you should now be able to see the swap size on htop.
# make changes permanent after reboot
sudo cp /etc/fstab /etc/fstab.bak
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Please note using swap as if it was RAM comes with a large penalty in terms of data movement.