Get started as a contributor#


Flower uses pyproject.toml to manage dependencies and configure development tools (the ones which support it). Poetry is a build tool which supports PEP 517.

Developer Machine Setup#


Some system-wide dependencies are needed.

For macOS#

  • Install homebrew. Don’t forget the post-installation actions to add brew to your PATH.

  • Install xz (to install different Python versions) and pandoc to build the docs:

    $ brew install xz pandoc

For Ubuntu#

Ensure you system (Ubuntu 22.04+) is up-to-date, and you have all necessary packages:

$ apt update
$ apt install build-essential zlib1g-dev libssl-dev libsqlite3-dev \
              libreadline-dev libbz2-dev libffi-dev liblzma-dev pandoc

Create Flower Dev Environment#

1. Clone the Flower repository from GitHub:

$ git clone
$ cd flower
  1. Let’s create the Python environment for all-things Flower. If you wish to use pyenv, we provide two convenience scripts that you can use. If you prefer using something else than pyenv, create a new environment, activate and skip to the last point where all packages are installed.

  • If you don’t have pyenv installed, the following script that will install it, set it up, and create the virtual environment (with Python 3.8.17 by default):

    $ ./dev/ <version> # once completed, run the bootstrap script
  • If you already have pyenv installed (along with the pyenv-virtualenv plugin), you can use the following convenience script (with Python 3.8.17 by default):

    $ ./dev/ <version> # once completed, run the `` script

3. Install the Flower package in development mode (think pip install -e) along with all necessary dependencies:

(flower-<version>) $ ./dev/

Convenience Scripts#

The Flower repository contains a number of convenience scripts to make recurring development tasks easier and less error-prone. See the /dev subdirectory for a full list. The following scripts are amongst the most important ones:

Create/Delete Virtual Environment#

$ ./dev/ <version> # Default is 3.8.17
$ ./dev/ <version> # Default is 3.8.17

Compile ProtoBuf Definitions#

$ python -m flwr_tool.protoc

Auto-Format Code#

$ ./dev/

Run Linters and Tests#

$ ./dev/

Add a pre-commit hook#

Developers may integrate a pre-commit hook into their workflow utilizing the pre-commit library. The pre-commit hook is configured to execute two primary operations: ./dev/ and ./dev/ scripts.

There are multiple ways developers can use this:

  1. Install the pre-commit hook to your local git directory by simply running:

    $ pre-commit install
    • Each git commit will trigger the execution of formatting and linting/test scripts.

    • If in a hurry, bypass the hook using --no-verify with the git commit command.

      $ git commit --no-verify -m "Add new feature"
  2. For developers who prefer not to install the hook permanently, it is possible to execute a one-time check prior to committing changes by using the following command:

    $ pre-commit run --all-files

    This executes the formatting and linting checks/tests on all the files without modifying the default behavior of git commit.

Run Github Actions (CI) locally#

Developers could run the full set of Github Actions workflows under their local environment by using Act. Please refer to the installation instructions under the linked repository and run the next command under Flower main cloned repository folder:

$ act

The Flower default workflow would run by setting up the required Docker machines underneath.

Build Release#

Flower uses Poetry to build releases. The necessary command is wrapped in a simple script:

$ ./dev/

The resulting .whl and .tar.gz releases will be stored in the /dist subdirectory.

Build Documentation#

Flower’s documentation uses Sphinx. There’s no convenience script to re-build the documentation yet, but it’s pretty easy:

$ cd doc
$ make html

This will generate HTML documentation in doc/build/html.

Note that, in order to build the documentation locally (with poetry run make html, like described below), Pandoc needs to be installed on the system.