Ed Morley
989351467f
The `libmemcached` package is available in the base stack image for all stacks newer than `cedar-14`, so at buildpack compile time the vendor step is skipped for those stacks: https://github.com/heroku/heroku-buildpack-python/blob/106f2997fa124852a2a35ee8bfa604ad20c47988/bin/steps/pylibmc#L12-L15 As such, it is not necessary to run the libmemcached bob-builder formula on newer stacks. The conditional has been updated so it correctly handles heroku-18 and also the upcoming heroku-20. An exit code of 1 has been used, otherwise `bob upload` will build and then upload a zero byte archive to S3, which will go unused. (This is in comparison to bob formulas that are nested, where an exit code of 0 is actually desirable, since it allows skipping steps.) Refs W-7485877. Co-authored-by: Joe Kutner <jpkutner@gmail.com>
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 based on python-version at build time.
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-3.8.2python-3.7.6python-3.6.10python-2.7.17
Tests
The buildpack tests use Docker to simulate Heroku's stack images.
To run the test suite:
make test
Or to test in a particular stack:
make test-heroku-18
make test-heroku-16
The tests are run via the vendored shunit2 test framework.