Python Poetry Buildpack

A Heroku Buildpack for Poetry users.

How to use

The Python Poetry Buildpack prepares the build to be processed by a Python buildpack such as heroku/python by generating requirements.txt and runtime.txt from poetry.lock. With that said, your repo cannot have a requirements.txt, it will be exported from Poetry (for runtime.txt see below).

To set up the use of several buildpacks from the Heroku CLI use buildpacks:add:

heroku buildpacks:clear
heroku buildpacks:add https://github.com/moneymeets/python-poetry-buildpack.git
heroku buildpacks:add heroku/python

Note: this buildpack is only for generating requirements.txt and runtime.txt for subsequent use by the official heroku/python buildpack. Do not depend on the installed Poetry's location, or its venv remaining functional at app runtime. If you need Poetry for other purposes (for example CI checks), make your own separate Poetry installation accordingly.

Configuration

Python

Python version can be forced by setting the PYTHON_RUNTIME_VERSION variable. Otherwise, it will be read from poetry.lock; for using Heroku default see below.

heroku config:set PYTHON_RUNTIME_VERSION=3.9.1

Poetry

Poetry version can be specified by setting POETRY_VERSION in Heroku config vars. Otherwise, it will default to a hardcoded version.

heroku config:set POETRY_VERSION=1.1.13

Generally all variables starting with POETRY_ are passed on to Poetry by this buildpack; see the corresponding Poetry documentation section for possible uses.

Exporting of development dependencies (e.g. to run tests in CI pipelines) can be optionally enabled by setting POETRY_EXPORT_DEV_REQUIREMENTS to 1:

heroku config:set POETRY_EXPORT_DEV_REQUIREMENTS=1

If you want to override the default export parameters (--without-hashes --with-credentials), you can set the POETRY_EXPORT_PARAMS config var. For example, you can use --with-hashes for added security, if you don't need git dependencies. This option is compatible with POETRY_EXPORT_DEV_REQUIREMENTS config var documented above.

heroku config:set POETRY_EXPORT_PARAMS=--with-hashes

runtime.txt

Generation of the runtime.txt can be skipped by setting DISABLE_POETRY_CREATE_RUNTIME_FILE to 1:

heroku config:set DISABLE_POETRY_CREATE_RUNTIME_FILE=1

If DISABLE_POETRY_CREATE_RUNTIME_FILE is set, the required Python version can be specified in runtime.txt. Otherwise, if runtime.txt is present in the repository, the buildpack will prevent the app from being deployed in order to avoid possible ambiguities.

Contributing

To test your changes locally run the (TAP-compatible) test suite:

bash run_tests.sh