Ed Morley
405c7651ea
`get-pip.py` is no longer used, since: - It uses `--force-reinstall`, which is unnecessary here and slows down repeat builds (given we call pip install every time now). Trying to work around this by using `get-pip.py` only for the initial install, and real pip for subsequent updates would mean we lose protection against cached broken installs, plus significantly increase the version combinations test matrix. - It means downloading pip twice (once embedded in `get-pip.py`, and again during the install, since `get-pip.py` can't install the embedded version directly). - We would still have to manage several versions of `get-pip.py`, to support older Pythons (once we upgrade to newer pip). We don't use `ensurepip` since: - not all of the previously generated Python runtimes on S3 include it. - we would still have to upgrade pip/setuptools afterwards. - the versions of pip/setuptools bundled with ensurepip differ greatly depending on Python version, and we could easily start using a CLI flag for the first pip install before upgrade that isn't supported on all versions, without even knowing it (unless we test against hundreds of Python archives). Instead we install pip using itself in wheel form. See: https://github.com/pypa/pip/issues/2351#issuecomment-69994524 The new pip wheel assets on S3 were generated using: ``` $ pip download --no-cache pip==19.1.1 Collecting pip==19.1.1 Downloading pip-19.1.1-py2.py3-none-any.whl (1.4 MB) Saved ./pip-19.1.1-py2.py3-none-any.whl Successfully downloaded pip $ pip download --no-cache pip==20.0.2 Collecting pip==20.0.2 Downloading pip-20.0.2-py2.py3-none-any.whl (1.4 MB) Saved ./pip-20.0.2-py2.py3-none-any.whl Successfully downloaded pip $ aws s3 sync . s3://lang-python/common/ --exclude "*" --include "*.whl" --acl public-read --dryrun (dryrun) upload: ./pip-19.1.1-py2.py3-none-any.whl to s3://lang-python/common/pip-19.1.1-py2.py3-none-any.whl (dryrun) upload: ./pip-20.0.2-py2.py3-none-any.whl to s3://lang-python/common/pip-20.0.2-py2.py3-none-any.whl $ aws s3 sync . s3://lang-python/common/ --exclude "*" --include "*.whl" --acl public-read upload: ./pip-19.1.1-py2.py3-none-any.whl to s3://lang-python/common/pip-19.1.1-py2.py3-none-any.whl upload: ./pip-20.0.2-py2.py3-none-any.whl to s3://lang-python/common/pip-20.0.2-py2.py3-none-any.whl ```
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.