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Pyproject Local Jupyter Kernel

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Separate dependencies for Jupyter notebooks - each notebook project can have its own dependencies!

Instead of installing a myriad of Jupyter kernelspecs, one per project, with this solution there is only one kernel provisioner that enables the environment for the project the notebook file resides in. This approach should be more portable, usable to anyone who checks out your project structure from git, and easier to use.

Pyproject Local supports Uv, Poetry, Hatch, Rye, and PDM and reads pyproject.toml to figure out which kind of project it is. Or it can use a custom command or a bare virtual environment directly.

screenshot of notebook launcher

Quick Start (JupyterLab)

  1. Install pyproject-local-kernel in your Jupyterlab environment and restart Jupyterlab
  2. Create a new directory for the notebook project
  3. Create a new notebook and select the Pyproject Local kernel
  4. In the “fallback” environment that appears - because it is an empty project - create a new project.

(Example for Uv:)

!uv init && uv add ipykernel

  1. Use the restart button in JupyterLab to restart the kernel after these changes.
  2. Dependencies will quickly sync and you are good to go!
  3. Use more add commands to add further dependencies.

See the examples directory for how to setup Jupyterlab and notebook projects separately. JupyterLab and the notebook are installed in separate environments.

Do you want to use pyproject-local-kernel in other environments, like with papermill, VSCodium or VS Code, or or other ways? See our FAQ for more information.

User Experience

If started in an empty directory or where a project is not correctly set up, the Pyproject Local will fail to start normally, but it will start a fallback kernel so that you can fix the project.

It will show a message like this - with some details about the error.

! Error: Could not find `ipykernel` in environment.
! Add `ipykernel` as a dependency in your project and update the virtual environment.
! The detected project type is: Unknown
!
! This is a fallback - pyproject-local-kernel failed to start.
! The purpose of the fallback is to let you run shell commands to fix the
! environment - when you are done, restart the kernel and try again!

Remember that you can also use Jupyterlab's embedded terminal to help setting up a project.

If pyproject.toml is Missing

If the Pyproject Local kernel is selected in a project where there is no pyproject.toml, then starting the kernel fails. On first run it should show an error message in JupyterLab.

If this happens, create a new pyproject.toml with the editor or use one of the project init commands to create a new project.

If the ipykernel is Missing

The notebook project needs to install ipykernel as a dependency.

Edit the pyproject.toml to include ipykernel in dependencies:

dependencies = [
    "ipykernel>=6.29",
    # .. more dependencies
]

sync the changes to the project using sync command for the project manager you use, then restart the Pyproject local kernel in Jupyterlab.

Configuration

Configuration is optional and is read from pyproject.toml. Only the pyproject.toml closest to the notebook is read. Defaults are based on “sniffing” the pyproject.toml to detect which project manager is in use.

python-cmd

The key tool.pyproject-local-kernel.python-cmd should be a command that runs python from the environment you want to use for the project.

If this is set then it overrides the default command. There is further explanation in the FAQ.

Default: Depends on project manager
Type: list[str] | str
Example:

[tool.pyproject-local-kernel]
python-cmd = ["uv", "run", "--with", "ipykernel", "python"]

use-venv

Path to virtual environment that should be used, relative to the pyproject.toml file. Can also be an absolute path.

If this is set then it overrides the default command - the virtualenv is used directly without invoking any project manager. Remember to explicitly install or sync required dependencies.

Default: Not set
Type: str
Example:

[tool.pyproject-local-kernel]
use-venv = ".venv"

sanity-check

If true, then run a check for ipykernel being installed in the project before starting the kernel process.

Default: true
Type: bool
Example:

[tool.pyproject-local-kernel]
sanity-check = true

PyprojectKernelProvisioner

The kernel provisioner is configurable in the same way as other Jupyter objects, with the following settings. They can be set in your jupyter_lab_config.py settings file. When possible, prefer to use settings in pyproject.toml instead, to keep them close to the project.

#------------------------------------------------------------------------------
# PyprojectKernelProvisioner(LocalProvisioner) configuration
#------------------------------------------------------------------------------
## Enable sanity check for 'ipykernel' package in environment
#  Default: True
# c.PyprojectKernelProvisioner.sanity_check = True

## Default setting for use-venv for projects using the 'use-venv' kernel
#  Default: '.venv'
# c.PyprojectKernelProvisioner.use_venv = '.venv'

About Particular Project Managers

The project manager command, be it rye, uv, pdm, etc needs to be available on the path where Jupyterlab runs. Either install the project manager in the Jupyterlab environment, or install the project manager user-wide (using something like pipx, uv tool, rye tools, brew, or other method to install it.)

Uv

  • Uv is detected if the pyproject.toml contains tool.uv. It is also the default fallback if no project manager is detected from a pyproject file.

  • The command used is uv run --with ipykernel python which means that it ensures ipykernel is used even if it's not already in the project(!). However, note that it uses an ephemeral virtual environment for ipykernel in that case. Add ipykernel to the project to avoid this.

Rye

  • Rye is detected if the pyproject.toml contains tool.rye.managed = true which Rye sets by default for its new projects.

PDM

  • PDM is detected if pyproject.toml contains tool.pdm

Hatch

  • Hatch is detected if pyproject.toml contains tool.hatch.envs

  • By default it calls out to hatch env find, to find the default virtualenv, and runs from there. hatch run should not be used directly because it's not compatible with how kernel interrupts work (as of this writing).

  • It's best to create the hatch project, add ipykernel as dependency and sync dependencies in a terminal before starting (it does not work so well with shell commands in a notebook).

Poetry

  • Poetry is detected if pyproject.toml contains tool.poetry.name

  • Some commands are interactive by default and don't work in a notebook, but they have an -n switch to make them non-interactive.

Project Status

Additional interest and maintainer help is welcomed.

License

pyproject-local-kernel is open source. See the LICENSE.md file in the source distribution for more information.