uv and pip

On Sunday November 3 I posted this to Mastodon:

I've somehow managed to get Python on my macbook to not install packages into the virtual environment I've activated and I'm honestly not sure how to fix this.

Has anyone else ever run into this problem? If so, any pointers on how to fix it?

I got lots of helpful replies and with those replies I was able to determine what the issue was and 'fix' it.

A timeline of events

I was working on updating a library of mine and because it had been a while since it had been worked on, I had to git clone it locally. When I did that I then set out to try uv for the virtual environment management.

This worked well (and was lightning FAST) and I was hacking away at the update I wanted to do.

Then I had a call with my daughter to review her upcoming schedule for the spring semester. When I got back to working on my library I kind of dove right in and started to get an error messages about the library not being installed

zsh: command not found: the-well-maintained-test

So I tried to install it (though I was 100% sure it was already there) and got this message

ERROR: Could not find an activated virtualenv (required).

I deleted the venv directory and started over again (using uv still) and ran into the same issue.

I restarted my Mac (at my day job I use Windows computers and this is just a natural reaction to do when something doesn't work the way I think it should1)

That didn't fix the issue 😢

I spent the next little while certain that in some way pipx or pyenv had jacked up my system, so I uninstalled them ... now you might ask why I thought this, and dear reader, I have no f$%&ing clue.

With those pesky helpers out of the way, pip still wasn't working the way I expected it to!

I then took to Mastodon and with this one response I saw what I needed

@ryancheley Are you running python -m pip install... Or just pip install...? If that's a venv created by uv, pip isn't installed I think, so 'pip install' might resolve to a pip in a different python installation

I went back to my terminal, and sure enough that was the issue. I haven't used uv enough to get a real sense of it, and when I was done talking with my daughter, my brain switched to Python programming, but it forgot that I had used uv to set everything up.

Lessons learned

This was a good lesson but I'm still unsure about a few things:

  1. How do I develop a cli using uv?
  2. Why did it seem that my cli testing worked fine right up until the call with my daughter, and now it seems that I can't develop cli's with uv?

I did write a TIL for this but I discovered that

uv venv venv

is not a full replacement for

python -m venv venv

Specifically uv does not include pip, which is what contributed to my issues. You can include pip by running this command though

uv venv venv --seed

Needless to say, with the help of some great people on the internet I got my issue resolved, but I did spend a good portion of Monday evening un-f$%&ing my MacBook Pro by reinstalling pyenv, and pipx2 ... and cleaning up my system Python for 3.12 and 3.13 ... turns out Homebrew REALLY doesn't want you to do anything with the system Python, even if you accidentally installed a bunch of cruft in there accidentally.

  1. Yes this is dumb, and yes I hate it ↩︎
  2. As of this writing I've uninstalled pipx because uv can replace it too. See Jeff Triplett's post uv does everything ↩︎

Posted by ryan on Sat 23 November 2024