My first impressions with pyenv
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pyenv provides an easy way to install almost any version of python from a large list of distributions. I have simply been using the version of python from...

Date: December 30, 2021

pyenv provides an easy way to install almost any version of python from a large list of distributions. I have simply been using the version of python from the os package manager for awhile, but recently I bumped my home system to Ubuntu 21.10 impish, and it is only 3.9+ while the libraries I needed were only compatable with up to 3.8.

│ I needed to install an older version of python on ubuntu

I’ve been wanting to check out pyenv for awhile now, but without a burning need to do so.

installing
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Based on the Readme it looked like I needed to install using homebrew,so this is what I did, but I later realized that there is a pyenv-installer repo that may have saved me this need.

Installing Homebrew on Linux </installing-homebrew-linux/>

List out install candidates
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You can list all of the available versions to install with pyenv install --list. It does reccomend updating pyenv if you suspect that it is missing one. At the time of writing this comes out to 532 different versions!

[code]
  pyenv install --list

Let’s install the latest 3.8 patch
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Installing a version is as easy as pyenv install 3.8.12. This will install it, but not make it active anywhere.

[code]
  pyenv install 3.8.12

let’s use python 3.8.12 while in this directory
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Running pyenv local will set the version of python that we wish to use while in this directory and any directory underneath of it while using the pyenv command.

[code]
  pyenv local python3.8.12

.python-version file
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This creates a .python-version files in the directory I ran it in, that contains simply the version number.

[code]
  3.8.12

using with pipx
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I immediately ran into the same issue I was having before when trying to run pipx, as pipx was running my system python. I had to install pipx in the python3.8 environment to get it to use it.

[code]
  pyenv exec pip install pipx
  pyenv exec pipx run kedro new

python is still the system python
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When I open a terminal and call python its still my system python that I installed and set with update-alternatives. I am not sure if this is expected or based on how I had installed the system python previously, but it’s what happened on my system.

[code]
  update-alternatives --query python

  Name: python
  Link: /home/walkers/.local/bin/python
  Status: auto
  Best: /usr/bin/python3
  Value: /usr/bin/python3

making a virtual environment </virtual-environment/>
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To make a virtual environment, I simply ran pyenv exec python in place of where I would normally run python and it worked for me. There is a whole package to get pyenv and venv to play nicely together, so I suspect that there is more to it, but this worked well for me and I was happy.

[code]
  pyenv exec python -m venv .venv --prompt $(basename $PWD)

Now when my virtual environment is active it points to the python in that virtual environment, and is the version of python that was used to create the environment.

Links
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https://github.com/pyenv/pyenv#installation