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?

Amr

Well, did you install Python 3.7 or not? If yes, fix your topic line. Then, what is the full output of the command you run? Preferably don't abbreviate but quote verbatim. That makes it searchable (which you have done before asking, right?) Also, Python itself doesn't require venv support, so maybe you need to install some more things... – Keon

Python3.7 is installed successfully by the commands above, however neither 'pip' nor any virtualenv system is installed. So the "and" part of my question is not satisfied; I think the question text stands. I'll update the question with the full output of the commands if you think that is useful. – Amr

To get pip: curl -O https://bootstrap.pypa.io/get-pip.py and to install pip: sudo python get-pip.py – Cordeliacordelie

To install virtualenv: pip install virtualenv and to use: virtualenv --python=<path/to/python/> /path/to/venv and source venv/bin/activate. You should see the name of your virtual environment as (venv) in your prompt. – Cordeliacordelie

The above commands only work on Debian/Ubuntu after doing apt install python3.7-distutils in addition to installing python. But then they do work. – Amr

Although this is not an answer - it looks to me that python3.7-venv is mostly a copy of python3.6-venv, including the system pip check; however, the package python3.7-pip doesn't exist for ubuntu bionic, leaving python 3.7 without a system pip. Overall, this looks like an ubuntu issue to me and should be fixed. – Grath

Not only Ubuntu issue. Similar behavior on vanilla Debian 9. – Cowpoke

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.

Amr

This answer does not address the original issue: Q asks for Ubuntu("bionic")-18.07 and the answer talks about another distribution, Debian("buster")-10.0. Problems related to python3venv are highly sensitive to: a) to the specific Debian/Ubuntu release we're talking about, b) whether the asked venv to install is the default for that distribution-release or an older/later one, and c) any customized apt-repos in /etc/apt/sources.list. – Flied

How and where to install python3.7, python3-venv and python3.7-venv packages that apy installs for us manually? Reason I am asking is because I cannot use yum with internet connection there need to download it from somewhere then be transferred. – Blaseio

Answer 2

sudo apt install python3-venv
python3 -m venv env

Oligocene

Please put your answer always in context instead of just pasting code. See here for more details. – Assentation

This is a wrong solution, you set up a virtualenv with default python, and on Ubuntu 18.04 default python is python3.6 not python3.7 . – Britzka

not only is it wrong, it's basically the same as the correct answer which came many months earlier, with the useful bits removed. – Liquidate