Heroku Buildpack: Python

This is the official Heroku buildpack for Python apps.

Recommended web frameworks include Django and Flask, among others. The recommended webserver is Gunicorn. There are no restrictions around what software can be used (as long as it's pip-installable). Web processes must bind to $PORT, and only the HTTP protocol is permitted for incoming connections.

Python packages with C dependencies that are not available on the stack image are generally not supported, unless manylinux wheels are provided by the package maintainers (common). For recommended solutions, check out this article for more information.

See it in Action

$ ls
my-application		requirements.txt	runtime.txt

$ git push heroku main
Counting objects: 4, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (4/4), 276 bytes | 276.00 KiB/s, done.
Total 4 (delta 0), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote:
remote: -----> Python app detected
remote: -----> Installing python
remote: -----> Installing pip
remote: -----> Installing SQLite3
remote: -----> Installing requirements with pip
remote:        Collecting flask (from -r /tmp/build_c2c067ef79ff14c9bf1aed6796f9ed1f/requirements.txt (line 1))
remote:          Downloading ...
remote:        Installing collected packages: Werkzeug, click, MarkupSafe, Jinja2, itsdangerous, flask
remote:        Successfully installed Jinja2-2.10 MarkupSafe-1.1.0 Werkzeug-0.14.1 click-7.0 flask-1.0.2 itsdangerous-1.1.0
remote:
remote: -----> Discovering process types
remote:        Procfile declares types -> (none)
remote:

A requirements.txt must be present at the root of your application's repository to deploy.

To specify your python version, you also need a runtime.txt file - unless you are using the default Python runtime version.

Current default Python Runtime: Python 3.6.12

Alternatively, you can provide a setup.py file, or a Pipfile. Using pipenv will generate runtime.txt at build time if one of the field python_version or python_full_version is specified in the requires section of your Pipfile.

Specify a Buildpack Version

You can specify the latest production release of this buildpack for upcoming builds of an existing application:

$ heroku buildpacks:set heroku/python

Specify a Python Runtime

Supported runtime options include:

• python-3.9.1
• python-3.8.7
• python-3.7.9
• python-3.6.12
• python-2.7.18

Tests

The buildpack tests use Docker to simulate Heroku's stack images.

To run the test suite against the default stack:

make test

Or to test against a particular stack:

make test STACK=heroku-16

To run only a subset of the tests:

make test TEST_CMD=tests/versions

The tests are run via the vendored shunit2 test framework.