Will Kahn-Greene: Switching from pyenv to uv

Premise

The 0.4.0 release of uv does everything I currently do with pip, pyenv, pipx, pip-tools, and pipdeptree. Because of that, I'm in the process of switching to uv.

This blog post covers switching from pyenv to uv.

History

• 2024-08-29: Initial writing.

• 2024-09-12: Minor updates and publishing.

Start state

I'm running Ubuntu Linux 24.04. I have pyenv installed using the the automatic installer. pyenv is located in $HOME/.pyenv/bin/.

I have the following Pythons installed with pyenv:

$ pyenv versions
  system
3.7.17
3.8.19
3.9.19
* 3.10.14 (set by /home/willkg/mozilla/everett/.python-version)3.11.9
3.12.3

I'm not sure why I have 3.7 still installed. I don't think I use that for anything.

My default version is 3.10.14 for some reason. I'm not sure why I haven't updated that to 3.12, yet.

In my 3.10.14, I have the following Python packages installed:

$ pip freeze
appdirs==1.4.4
argcomplete==3.1.1
attrs==22.2.0
cffi==1.15.1
click==8.1.3
colorama==0.4.6
diskcache==5.4.0
distlib==0.3.8
distro==1.8.0
filelock==3.14.0
glean-parser==6.1.1
glean-sdk==50.1.4
Jinja2==3.1.2
jsonschema==4.17.3
MarkupSafe==2.0.1
MozPhab==1.5.1
packaging==24.0
pathspec==0.11.0
pbr==6.0.0
pipx==1.5.0
platformdirs==4.2.1
pycparser==2.21
pyrsistent==0.19.3
python-hglib==2.6.2
PyYAML==6.0
sentry-sdk==1.16.0
stevedore==5.2.0
tomli==2.0.1
userpath==1.8.0
virtualenv==20.26.2
virtualenv-clone==0.5.7
virtualenvwrapper==6.1.0
yamllint==1.29.0

That probably means I installed the following in the Python 3.10.14 Python environment:

• MozPhab

• pipx

• virtualenvwrapper

Maybe I installed some other things for some reason lost in the sands of time.

Then I had a whole bunch of things installed with pipx.

I have many open source projects all of which have a .python-version file listing the Python versions the project uses.

I think that covers the start state.

Steps

First, I made a list of things I had.

• I listed all the versions of Python I have installed so I know what I need to reinstall with uv.

  $ pyenv versions
  

• I listed all the packages I have installed in my 3.10.14 environment (the default one).

  $ pip freeze
  

• I listed all the packages I installed with pipx.

  $ pipx list
  

I uninstalled all the packages I installed with pipx.

$ pipx uninstall PACKAGE

Then I uninstalled pyenv and everything it uses. I followed the pyenv uninstall instructions:

$ rm -rf $(pyenv root)

Then I removed the bits in my shell that add to the PATH and set up pyenv and virtualenvwrapper.

Then I started a new shell that didn't have all the pyenv and virtualenvwrapper stuff in it.

Then I installed uv using the uv standalone installer.

Then I ran uv --version to make sure it was installed.

Then I installed the shell autocompletion.

Note

I have a dotfiles thing and separate out bashrc changes by what changes them. You can see my home-grown thing that works for me here:

https://github.com/willkg/dotfiles

These instructions are specific to my home-grown dotfiles thing.

$ echo'eval "$(uv generate-shell-completion bash)"'>> ~/dotfiles/bash.d/20-uv.bash

Then I started a new shell to pick up those changes.

Then I installed Python versions:

$ uv python install 3.8 3.9 3.10 3.11 3.12
Searching for Python versions matching: Python 3.10
Searching for Python versions matching: Python 3.11
Searching for Python versions matching: Python 3.12
Searching for Python versions matching: Python 3.8
Searching for Python versions matching: Python 3.9
Installed 5 versions in8.14s
 + cpython-3.8.19-linux-x86_64-gnu
 + cpython-3.9.19-linux-x86_64-gnu
 + cpython-3.10.14-linux-x86_64-gnu
 + cpython-3.11.9-linux-x86_64-gnu
 + cpython-3.12.5-linux-x86_64-gnu

When I type "python", I want it to be a Python managed by uv. Also, I like having "pythonX.Y" symlinks, so I created a uv-sync script which creates symlinks to uv-managed Python versions:

https://github.com/willkg/dotfiles/blob/main/dotfiles/bin/uv-sync

Then I installed all my tools using uv tool install.

$ uv tool install PACKAGE

For tox, I had to install the tox-uv package in the tox environment:

$ uv tool install --with tox-uv tox

Now I've got everything I do mostly working.

So what does that give me?

I installed uv and I can upgrade uv using uv self update.

Python interpreters are managed using uv python. I can create symlinks to interpreters using uv-sync script. Adding new interpreters and removing old ones is pretty straight-forward.

When I type python, it opens up a Python shell with the latest uv-managed Python version. I can type pythonX.Y and get specific shells.

I can use tools written in Python and manage them with uv tool including ones where I want to install them in an "editable" mode.

I can write scripts that require dependencies and it's a lot easier to run them now.

I can create and manage virtual environments with uv venv.

Next steps

Delete all the .python-version files I've got.

Update documentation for my projects and add a uv tool install PACKAGE option to installation instructions.

Probably discover some additional things to add to this doc.