JupyterLab extensions#

JupyterLab is designed as an extensible environment. In doing so, JupyterLab extensions can customise any part of JupyterLab. They can provide new themes, file viewers and editors, or renderers for rich outputs in Notebook.

Installing extensions#

A JupyterLab extension contains JavaScript that is installed in JupyterLab and executed in the browser. Most JupyterLab extensions can be installed with pip. These packages can also contain server-side components that are required for the extension to function.

Since JupyterLab ≥ 4, the default extension manager uses PyPI as a source for the available extensions and pip to install them. An extension is listed if the Python package has the trove classifier Framework :: Jupyter :: JupyterLab :: Extensions :: Prebuilt.

Warning

It does not check if the extension is compatible with the current JupyterLab version.

Danger

Installing an extension allows arbitrary code to be executed on the server, kernel and browser. Therefore, avoid installing extensions that you do not trust.

Configuring the Extension Manager#

By default, there are two extension managers provided by JupyterLab:

pypi: Default setting that allows the installation from pypi.org.
readonly: shows the installed extensions with the possibility to disable or enable them.

You can specify the manager with the command line option --LabApp.extension_manager, for example jupyter lab --LabApp.extension_manager=readonly.

When searching for extensions in the extension manager, JupyterLab usually shows all search results and any source extension can be installed. However, to increase security, JupyterLab can be configured so that extensions can only be activated using the block or allow lists.

You can define the loading of the lists with blocked_extensions_uris or allowed_extensions_uris, which contain a list of comma-separated URIs, for example --LabServerApp.blocked_extensions_uris=http://example.com/blocklist.json with the following blocklist.json file:

{
  "blocked_extensions": [
    {
      "name": "@jupyterlab-examples/launcher",
      "type": "jupyterlab",
      "reason": "@jupyterlab-examples/launcher is blocklisted for test purpose - Do NOT take this for granted!!!",
      "creation_date": "2020-03-11T03:28:56.782Z",
      "last_update_date":  "2020-03-11T03:28:56.782Z"
    }
  ]
}

Another example shows an allowlist.json file that allows all extensions of the JupyterLab organisation:

{
  "allowed_extensions": [
    {
      "name": "@jupyterlab/*",
      "type": "jupyterlab",
      "reason": "All @jupyterlab org extensions are allowed, of course…",
      "creation_date": "2020-03-11T03:28:56.782Z",
      "last_update_date":  "2020-03-11T03:28:56.782Z"
    }
  ]
}