You can install JupyterLab extensions through the JupyterLab GUI directly, these extensions will be persisted (across interactive sessions) automatically.
JupyterLab also supports server extensions. To install these extensions, navigate to Settings > Configure JupyterLab. Here you can install extensions like you normally would using commands such as:
pip install jupyterlab-git
In addition, you can install extensions from
npm through the
jupyter labextension install jupyterlab-spreadsheet
To build the JupyterLab image you need to make sure there are no interactive sessions running.
User settings that are configured through the JupyterLab GUI, such as your JupyterLab Theme or Text Editor Key Map, are persisted automatically. It just works.