Can't initialize the interpreter: "Python downloads are set to 'manual'"

[biofilos]

I am trying to follow the docs to test Pythonx. However, when I try to run

Pythonx.uv_init("""
        [project]
        name = "project"
        version = "0.0.0"
        requires-python = "==3.10.*"
        dependencies = [
          "numpy==2.2.2"
        ]
        """)

I get the error

error: No interpreter found for Python ==3.10.* in managed installations

hint: A managed Python download is available for Python ==3.10.*, but Python downloads are set to 'manual', use `uv python install ==3.10.*` to install the required version
** (RuntimeError) fetching Python and dependencies failed, see standard output for details
    (pythonx 0.4.7) lib/pythonx/uv.ex:37: Pythonx.Uv.fetch/3
    (pythonx 0.4.7) lib/pythonx.ex:60: Pythonx.uv_init/2
    iex:2: (file)

I tried using :force and varying the uv version with the same result. Is there something I am missing?

[josevalim]

Try setting this to automatic: https://docs.astral.sh/uv/concepts/python-versions/#disabling-automatic-python-downloads

But I assume in order for it to be manual, you have a config file either locally or in your system that turned it off? 🤔

[biofilos]

Thanks a lot for your prompt reply!

I would have never solved this unless you pointed me on the right direction
Turns out, I had uv installed using dnf in Fedora, and it sets python-downloads = "manual" in /etc/uv/uv.toml.

I leave this here in case someone has a similar issue

Thanks a lot for all your work on Elixir!!
Cheers!!

[josevalim]

Maybe we should force it to automatic? 🤔

[jonatanklosko]

I think we should ignore any global config altogether, because it can be a source of non-reproducability. If someone complains we can always add an option to enable it explicitly. @josevalim wdyt?

[josevalim]

Yeah, worth giving it a try like that!