OpenFisca Extension-Template

This repository is here to help you bootstrap your own OpenFisca extension package.

You should NOT fork it but follow the set up instructions below.

Otherwise, you will have to clean up all tags when you deploy your own extension package.

Setting up your Extension Package

This set of instructions only needs to be followed once and will create your own copy of this boilerplate directory, customising it to the country you want to work on. You will need to have Git installed.

Using GitHub (recommended for GitHub users)

1. Click on the “Use this template” dropdown and select “Create a new repository”.

2. Set the repository name to openfisca-<your_city_name>; use underscore _ as separator if there are spaces in the city name. For example, openfisca-ile_d-yeu or openfisca-valparaiso.

3. After being redirected to your newly created repository, please allow a few minutes for the automatic setup to be executed. Once done, the title of the README file should be updated to OpenFisca <your_city_name>.

If the automatic setup does not start within a few minutes, you can initiate it manually:

• Navigate to the “Actions” tab.
• Select the “First time setup” workflow.
• Click on “Run workflow” to start the setup process manually.

4. Follow the instructions in the new repository's README.md.

Manual setup (recommended for users of other Git hosts)

1. Download a copy of this repository, unzip it and cd into it in a Terminal window.

2. Create a new repository on your favourite git host (Bitbucket, GitLab, …) with the name openfisca-<your_city_name>. For example, openfisca-vina_del_mar or openfisca-paris.

3. Execute the first-time-setup.sh script to initialise the git repository. This performs numerous tasks including replacing all references to openfisca-extension_template with references to the new extension package.

   • To execute the script run bash first-time-setup.sh from the command line
   • After the first-time-setup.sh has run both it and these instructions are removed.

4. Follow the instructions in the new repository's README.md.

Writing the Legislation

The city or jurisdiction whose law is modelled here has a very simple tax and benefit system.

• It has a child allowance that only applies to your city.

This and other elements are described in different folders. All the modelling happens within the src/openfisca_<my_city> folder.

• The rates are in the parameters folder.
• The formulas are in the variables folder.

The files that are outside from the src/openfisca_<my_city> folder are used to set up the development environment.

Packaging your Extension Package for Distribution

City packages are Python distributions. You can choose to distribute your package automatically via the predefined continuous deployment system on GitHub Actions, or manually.

Automatic continuous deployment on GitHub

This repository is configured with a continuous deployment system to automate the distribution of your package via pip.

Setting up continuous deployment

To activate the continuous deployment:

1. Create an account on PyPI if you don't already have one.
2. Generate a token in your PyPI account. This token will allow GitHub Actions to securely upload new versions of your package to PyPI.
3. Add this token to your GitHub repository's secrets under the name PYPI_TOKEN.

Once set up, changes to the main branch will trigger an automated workflow to build and publish your package to PyPI, making it available for pip installation.

Manual distribution

If you prefer to manually manage the release and distribution of your package, follow the guidelines provided by the Python Packaging Authority.

This involves detailed steps on preparing your package, creating distribution files, and uploading them to PyPI.

Install Instructions for Users and Contributors

This package requires Python 3.9. More recent versions should work, but are not tested.

All platforms that can execute Python are supported, which includes GNU/Linux, macOS and Microsoft Windows.

Setting-up a Virtual Environment with venv

In order to limit dependency conflicts, we recommend using a virtual environment with venv.

• A venv is a project specific environment created to suit the needs of the project you are working on.

To create a virtual environment, launch a terminal on your computer, cd into your directory and follow these instructions:

python3 -m venv .venv # create a new virtual environment in the “.venv” folder, which will contain all dependencies
source .venv/bin/activate # activate the venv

You can now operate in the venv you just created.

You can deactivate that venv at any time with deactivate.

:tada: You are now ready to install this OpenFisca Extension Package!

Two install procedures are available. Pick procedure A or B below depending on how you plan to use this Extension Package.

A. Minimal Installation (Pip Install)

Follow this installation if you wish to:

• run calculations on a large population;
• create tax & benefits simulations;
• serve your Extension Package with the OpenFisca Web API.

For more advanced uses, head to the Advanced Installation.

Install this Extension Package with Pip Install

Inside your venv, check the prerequisites:

python --version  # should print at least "Python 3.9.xx".

pip --version  # should print at least 9.0.
# if not, run "pip install --upgrade pip"

Install the Extension Package:

pip install openfisca-<my_city>

:warning: Please beware that installing the Extension Package with pip is dependent on its maintainers publishing said package.

:tada: This OpenFisca Extension Package is now installed and ready!

Next Steps

• To learn how to use OpenFisca, follow our tutorials.
• To serve this Extension Package, serve the OpenFisca Web API.

Depending on what you want to do with OpenFisca, you may want to install yet other packages in your venv:

• To write on top of this Extension Package, head to the Extensions documentation.
• To plot simulation results, try matplotlib.
• To manage data, check out polars.

B. Advanced Installation (Git Clone)

Follow this tutorial if you wish to:

• create or change this Extension Package's legislation;
• contribute to the source code.

Clone this Extension Package with Git

First, make sure Git is installed on your machine.

Set your working directory to the location where you want this OpenFisca Extension Package cloned.

We recommend you to use an isolated environment manager to manage build and extension dependencies separately:

pipx install poetry

Poetry will automatically manage a virtual environment for you. Nonetheless, if you need to have more control over your dependencies, we recommend you to use a virtualenv:

poetry config settings.virtualenvs.create false
pyenv install 3.9.xx
pyenv virtualenv 3.9.xx openfisca

Clone this Extension Package on your machine:

git clone https://example.com/repository.git
cd repository_folder

Inside your venv, check the prerequisites:

pyenv local openfisca
python --version  # should print "Python 3.9.xx".
poetry install --all-extras --sync

You can make sure that everything is working by running the provided tests with poetry run openfisca test --country-package=openfisca_country_template --extensions=openfisca_extension_template tests/openfisca_extension_template.

Learn more about tests

:tada: This OpenFisca Extension Package is now installed and ready!

Cleanup (optional)

To completely clean up your environment, run:

poetry env remove --all
pip freeze | grep -v "^-e" | sed "s/@.*//" | xargs pip uninstall -y

This will remove all pip package from current environment and remove all Poetry environment in OpenFisca Extension-Template.

Next Steps

• To write new legislation, read the Coding the legislation section to know how to write legislation.
• To contribute to the code, read our Contribution Guidebook.

C. Contributing

Follow this tutorial if you wish to:

• contribute to the source code.

Note: This tutorial assumes you have already followed the instructions laid out in section B. Advanced Installation.

In order to ensure all published versions of this template work as expected, new contributions are tested in an isolated manner on Github Actions.

Follow these steps to set up an isolated environment for testing your contributions as Github Actions does.

Set up an isolated environment

First, make sur Tox is installed on your machine.

We recommend using pipx to install tox, to avoid mixing isolated-testing dependencies testing with virtualenv.

pipx install tox

Testing your contribution in an isolated environment

You can make sure that your contributions will work as expected by running:

tox

You can also run these in parallel:

tox -p

:tada: Your contribution to OpenFisca Extension Package is now ready for prime time!

Next Steps

• Open a pull request to the main branch of this repository.
• Announce your changes as described in CONTRIBUTING.

Serve this Extension Package with the OpenFisca Web API

If you are considering building a web application, you can use the packaged OpenFisca Web API with your Extension Package.

To serve the Openfisca Web API locally, run:

openfisca serve --port 5000 --country-package openfisca_country_template --extensions openfisca_<my_city>

Or use the quick-start task command:

task serve

To read more about the openfisca serve command, check out its documentation.

You can make sure that your instance of the API is working by requesting:

curl "http://localhost:5000/spec"

This endpoint returns the Open API specification of your API.

:tada: This OpenFisca Extension Package is now served by the OpenFisca Web API! To learn more, go to the OpenFisca Web API documentation.