Using a custom Pyodide distribution

Beneath custom wheels are the raw JS and WebAssembly parts of the kernel provided by pyodide. As the full distribution is very large, and self-hosting of all its assets brings their own challenges, this use of CDN is the default for JupyterLite.

A custom pyodide.js, along with its packages.json and the rest of its assets, such as might be downloaded via the --pyodide CLI option, can also be configured. This can be either relative to the lite_dir, or as a full URL.

First if you don’t have a jupyter-lite.json file, create one where you will be executing the jupyter lite build command. Then add the following content to the file, or just the litePluginSettings section if you have some previous configuration already:

{
  "jupyter-lite-schema-version": 0,
  "jupyter-config-data": {
    "litePluginSettings": {
      "@jupyterlite/pyodide-kernel-extension:kernel": {
        "pyodideUrl": "./path/to/custom/pyodide/pyodide.js"
      }
    }
  }
}

Then proceed with a new build (jupyter lite build) to make sure the file is correctly generated in the output directory.

Hint

The performance of extracting a pyodide .tar.bz2 can be improved by installing libarchive-c: see the extensions page.