Trivial default.nix setup times out on Binder

[l0b0]

Bug description

The following default.nix setup times out on Binder:

{ pkgs ? import
    (
      fetchTarball {
        name = "21.11";
        url = "https://github.com/NixOS/nixpkgs/archive/a7ecde854aee5c4c7cd6177f54a99d2c1ff28a31.tar.gz";
        sha256 = "162dywda2dvfj1248afxc45kcrg83appjd0nmdb541hl7rnncf02";
      }
    )
    { }
}:
(
  pkgs.python3.withPackages (
    ps: [
      ps.bash_kernel
      ps.jupyterlab
    ]
  )
)

Expected behaviour

Should work as well as nix-shell --pure --run 'jupyter lab intro.ipynb' works locally.

Actual behaviour

Times out after a few minutes; see logs.

How to reproduce

1. Go to https://mybinder.org/v2/gl/victor-engmark%2Fbash-scripting-intro/HEAD?labpath=intro.ipynb
2. Wait for it to time out

Your personal set up

Not applicable, and I don't know what the values are on Binder.

[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! 🎉

[meeseeksmachine]

This issue has been mentioned on Jupyter Community Forum. There might be relevant details there:

https://discourse.jupyter.org/t/trivial-nix-based-notebook-fails-to-load/13172/5

[robertodr]

This is still an issue. Not even the examples repository works.

[jezcope]

Yup, I've run into this when trying some things out thinking how #1300 might be implemented.

The weird thing is that running repo2docker locally for a nix-based repository works fine so I guess it's something to do with how JupyterHub detects that the container is ready?