python - How to install python3.7 and create a virtualenv with pip on Ubuntu 18.04?

Question

I'm trying to set up a standard virtual-environment(venv) with python 3.7 on Ubuntu 18.04, with pip (or some way to install packages in the venv). The standard way to install python3.7 seems to be:

% sudo apt install python3.7 python3.7-venv
% python3.7 -m venv py37-venv

but the second command fails, saying:

The virtual environment was not created successfully because ensurepip is not available. On Debian/Ubuntu systems, you need to install the python3-venv package using the following command.

apt-get install python3-venv

You may need to use sudo with that command. After installing the python3-venv package, recreate your virtual environment.

Failing command: ['/py37-venv/bin/python3.7', '-Im', 'ensurepip', '--upgrade', '--default-pip']

This is true; there is no ensurepip nor pip installed with this python. And I did install python3.7-venv already (python3-venv is for python3.6 on Debian/Ubuntu). I gather there has been some discussion about this in the python community because of multiple python versions and/or requiring root access, and alternate ways to install python modules via apt or similar.

Creating a venv without pip (--without-pip) succeeds, but then there's no way to install packages in the new venv which seems to largely defeat the purpose.

So what's the accepted "best practice" way to install and use python3.7 on 18.04 with a venv?

Answer 1

I don't know if it's best practices or not, but if I also install python3-venv and python3.7-venv then everything works (this is tested on a fresh stock Debian buster docker image):

% sudo apt install python3.7 python3-venv python3.7-venv
% python3.7 -m venv py37-venv
% . py37-venv/bin/activate
(py37-venv) % 

Note that it also installs all of python3.6 needlessly, so I can't exactly say I like it, but at least it does work and doesn't require running an unsigned script the way get-pip.py does.