Add support for the .python-version
file
#1664
Merged
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Following on from the recent Python version refactoring in #1658, this now adds support for configuring the app's Python version using a
.python-version
file. This file is used by several tools in the Python ecosystem (such as pyenv,actions/setup-python
, uv), whereas the existingruntime.txt
file is proprietary to Heroku.This change is the classic Python buildpack equivalent of the Python CNB change here:
heroku/buildpacks-python#272
If both a
runtime.txt
file and a.python-version
file are present, then theruntime.txt
file will take precedence. However, use of the.python-version
file is now recommended, sinceruntime.txt
will be deprecated in the future. Both theruntime.txt
file and.python-version
file take precedence over any Python version specified in aPipfile.lock
for Pipenv users.We support the following
.python-version
syntax:3.13
, which will then be resolved to the latest Python 3.13). (This form is recommended, since it allows for Python security updates to be pulled in without having to manually bump the version.)3.13.0
)#
)We don't support the following
.python-version
features:python-
(since this form is undocumented and will likely be deprecated by pyenv in the future)In addition, the existing
runtime.txt
support has been updated to allow specifying just the major Python version, in order to increase feature parity between the files, and avoid confusion if users try to use the major version only syntax from.python-version
in theirruntime.txt
.Closes #913.
Closes #932.
GUS-W-7671453.
GUS-W-16821357.