Using pyenv to install Python and create a virtual environment

Posted on Sat 10 October 2020 in Development

A few days ago Python 3.9.0 has been released and I really wanted to test ist latest features (maybe I will do a separate post to talk about them) without messing my system with another Python version.

To manage my Python versions I've been using pyenv for a while and once configured, it's very easy to install a new Python version.

Make sure your pyenv is updated

You should have at least pyenv 1.2.21 if you want to test Python 3.9.0 In case you haven't updated it and you are using MacOS, you can do it with this command:

brew update && brew upgrade pyenv

once installed you should see the latest version:

pyenv --version
pyenv 1.2.21

Install Python 3.9.0

To install Python 3.9.0 you only need pyenv install 3.9.0:

pyenv install 3.9.0
python-build: use [email protected] from homebrew
python-build: use readline from homebrew
Downloading Python-3.9.0.tar.xz...
-> https://www.python.org/ftp/python/3.9.0/Python-3.9.0.tar.xz
Installing Python-3.9.0...
python-build: use readline from homebrew
python-build: use zlib from xcode sdk
Installed Python-3.9.0 to /Users/andrea/.pyenv/versions/3.9.0

Set Python 3.9.0 as the local version

Now that the version you want has been installed, you need to tell pyenv you want to use it:

pyenv local 3.9.0
pyenv which python
/Users/andrea/.pyenv/versions/3.9.0/bin/python

Install virtualenvwrapper for pyenv

pyenv needs its own installation of virtualenvwrapper to manage virtualenvs. You can configure it using pyenv virtualenvwrapper:

pyenv virtualenvwrapper
Collecting virtualenvwrapper
Using cached virtualenvwrapper-4.8.4.tar.gz (334 kB)
Collecting virtualenv
Downloading virtualenv-20.0.33-py2.py3-none-any.whl (4.9 MB)
    |████████████████████████████████| 4.9 MB 4.1 MB/s
Collecting virtualenv-clone
Using cached virtualenv_clone-0.5.4-py2.py3-none-any.whl (6.6 kB)
Collecting stevedore
Downloading stevedore-3.2.2-py3-none-any.whl (42 kB)
    |████████████████████████████████| 42 kB 2.7 MB/s
Collecting six<2,>=1.9.0
Using cached six-1.15.0-py2.py3-none-any.whl (10 kB)
Collecting filelock<4,>=3.0.0
Using cached filelock-3.0.12-py3-none-any.whl (7.6 kB)
Collecting distlib<1,>=0.3.1
Using cached distlib-0.3.1-py2.py3-none-any.whl (335 kB)
Collecting appdirs<2,>=1.4.3
Using cached appdirs-1.4.4-py2.py3-none-any.whl (9.6 kB)
Collecting pbr!=2.1.0,>=2.0.0
Using cached pbr-5.5.0-py2.py3-none-any.whl (106 kB)
Using legacy 'setup.py install' for virtualenvwrapper, since package 'wheel' is not installed.
Installing collected packages: six, filelock, distlib, appdirs, virtualenv, virtualenv-clone, pbr, stevedore, virtualenvwrapper
    Running setup.py install for virtualenvwrapper ... done
Successfully installed appdirs-1.4.4 distlib-0.3.1 filelock-3.0.12 pbr-5.5.0 six-1.15.0 stevedore-3.2.2 virtualenv-20.0.33 virtualenv-clone-0.5.4 virtualenvwrapper-4.8.4

Create a virtual environment using Python from pyenv

At this point you can create the virtual environment based on Python 3.9.0 using this command mkvirtualenv -p $(pyenv which python) py39-test:

mkvirtualenv -p $(pyenv which python) py39-test
created virtual environment CPython3.9.0.final.0-64 in 1394ms
creator CPython3Posix(dest=/Users/andrea/.virtualenvs/py39-test, clear=False, global=False)
seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/Users/andrea/Library/Application Support/virtualenv)
    added seed packages: pip==20.2.3, setuptools==50.3.0, wheel==0.35.1
activators BashActivator,CShellActivator,FishActivator,PowerShellActivator,PythonActivator,XonshActivator
virtualenvwrapper.user_scripts creating /Users/andrea/.virtualenvs/py39-test/bin/predeactivate
virtualenvwrapper.user_scripts creating /Users/andrea/.virtualenvs/py39-test/bin/postdeactivate
virtualenvwrapper.user_scripts creating /Users/andrea/.virtualenvs/py39-test/bin/preactivate
virtualenvwrapper.user_scripts creating /Users/andrea/.virtualenvs/py39-test/bin/postactivate
virtualenvwrapper.user_scripts creating /Users/andrea/.virtualenvs/py39-test/bin/get_env_details

Check you are using the correct Python version

(py39-test) ➜  ~ python --version
Python 3.9.0

As you can see from the above output, we have created a new virtualenv using Python 3.9.0 which has been installed through pyenv.