2021-01-25
Time for Python 2 users to make sure we have a copy of Pip and other pieces
The news of the time period is that as the Pip developers said they
would, the just released Pip 21.0 has dropped support for Python
2 (via). In
theory this doesn't matter for modern users of Python 2.7, because
Python itself should ship with a bundled version of pip so that you
don't have to install one from scratch. In practice, some Linux
distributions split the pip command off into a separate sub-package
and no longer make a Python 2 version available, although they
continue to ship Python 2 itself for legacy uses (this is the case
in Fedora 32 and later). Now that Pip no longer supports Python 2,
I wouldn't be surprised if more Linux (and Unix) distributions did
this, because Pip's change means that they need to ship two different
versions of Pip.
The release of Pip 21.0 and all of this has made me realize that now is
a good time for us (and for all Python 2 users) to make sure that we
have our own working copy of Pip, quite possibly the latest one. This
is unfortunately now more difficult than it used to be just a week or
two ago, because the special get-pip.py bootstrap
Python program is now Pip 21.0, and so won't work with Python 2 any
more. Fortunately you can still find the older version of get-pip.py
for Python 2.7. You
might want to save a copy, or go all the way to making a '--user'
install of the Python 2 pip in some user account and saving the
.local/lib/python2.7/site-packages/pip and other artifacts that you get.
To the best of my knowledge they can be moved around freely between
systems.
Of course, Pip itself relies on the Python Package Index (PyPI). My understanding is that PyPI has not made any
announcements about dropping support for Python 2 packages or for
Python 2 versions of pip fetching packages, but I wouldn't count
on either being available forever. If you have additional dependencies
for your Python 2 programs, it's probably a good time to make sure
you have local copies of them. This especially includes dependencies
that you get through packages provided by your Linux distribution
(for example as Ubuntu packages), because pretty much every Linux
distribution will be dropping most or all of their additional Python
2 packages soon (if they haven't already).
(If nothing else, someday PyPI may change its API in a way that requires changes to Pip and other programs that talk to it.)
I also wouldn't be surprised if Pip's move prompts more third party Python packages to drop support for Python 2, which is of course a movement that's been going on for some time now. Presumably this doesn't matter much to most Python 2 people, who have probably already more or less frozen their package versions.
(Fortunately we have very little to worry about. I believe that almost all of our remaining Python 2 code uses only built in modules, not third-party packages. Our major consumer of third party packages is already a Python 3 program.)
PS: While PyPy is going to provide a Python 2.7 implementation for the foreseeable future, I wouldn't count on the rest of the Python ecosystem to support it (Pip included, obviously). People who use the Python 2 PyPy, perhaps someday including us, will be on their own.