Setting frontend.base_url

[kmbae]

Description

I just wonder about setting the base_url for the jupyverse.
For instance, when running jupyter lab, the --LabApp.base_url option modifies the URL while connecting via browser.
I thought that --set frontend.base_url=/test/ works the same as --LabApp.base_url=/test.
But this option does not behave as I expected. Any solutions?

Reproduce

1. Run jupyverse using below code
   jupyverse --set kernels.require_yjs=true --set jupyterlab.server_side_execution=true --set auth.mode=noauth --set frontend.collaborative=true --set frontend.base_url=/ --host 0.0.0.0 --port 8888 --allow-origin '*'

2. access the jupyverse using browser and obtained below screen.
   http://ipaddr:8888/lab

3. Run jupyverse using below code with base_url option
   jupyverse --set kernels.require_yjs=true --set jupyterlab.server_side_execution=true --set auth.mode=noauth --set frontend.collaborative=true --set frontend.base_url=/test/ --host 0.0.0.0 --port 8888 --allow-origin '*'

4. access the jupyverse using browser and obtained below screen.
   http://ipaddr:8888/test/lab

Expected behavior

Expected to have the same screenshot for both options.

Context

• Operating System and version:
• Browser and version:
• Jupyter Server version:

Troubleshoot Output

Paste the output from running `jupyter troubleshoot` from the command line here.
You may want to sanitize the paths in the output.

Command Line Output

Paste the output from your command line running `jupyter lab` here, use `--debug` if possible.

Browser Output

Paste the output from your browser Javascript console here, if applicable.

[welcome]

Thank you for opening your first issue in this project! Engagement like this is essential for open source projects! 🤗

If you haven't done so already, check out Jupyter's Code of Conduct. Also, please try to follow the issue template as it helps other other community members to contribute more effectively.

You can meet the other Jovyans by joining our Discourse forum. There is also an intro thread there where you can stop by and say Hi! 👋

Welcome to the Jupyter community! 🎉

[rakhmaevao]

Hi. The frontend.base_url parameter is used for correct redirects inside the frontend application (for example, jupyterlab). This must be set if you set the prefix at the level of the external proxy.

To add a prefix at the level of the entire Jupyverse, in addition to the frontend.base_url configuration, you also need to set root_path in FastApi app. Unfortunately, there is no CLI setting for this parameter. But you can do this through a plugin in which you override this parameter of the FastApi application.

For example:

class MyPluginComponent(Component):
    async def start(
        self,
        ctx: Context,
    ) -> None:
        app = await ctx.request_resource(App)
        app._app.root_path = "/test"

If any of the maintainers consider this necessary, then I can add such an option to CLI.

What do you say, @davidbrochart?