Ed Morley
2097eab028
Before: - if `wheel` was not already installed, then `get-pip.py` would automatically install the latest version on PyPI, which is `0.34.2` (or `0.33.6` for Python 3.4). - if `wheel` was already installed, then it was left unchanged regardless of the version installed. Now: - if `wheel` is not already installed, then the same versions will be installed as before, except these versions are pinned and will now not change unexpectedly after future `wheel` releases. - if `wheel` is already installed, then it's upgraded/downgraded to the target version as needed. Partly addresses #1000, though this change only helps builds where the pip/setuptools/wheel install flow is triggered (currently only new apps or ones where Python was purged or pip was not the correct version). Since the wheel version is now known, it's output to the build log to ease debugging and for parity with pip/setuptools. The rest of #1000 will be fixed in later commits.
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 master
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-3.7.4
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 3.6.9
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-3.8.5python-3.7.8python-3.6.11python-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.