Update allowed images without restarting JupyterHub

JupyterHub
1

Hello,

Is there a way to update allowed_images in jupyterhub_config.py without restarting Docker container running JupyterHub?

I had two ideas:

  • I can make this work maybe with setting remove=False and not removing user servers, but this answer says that it is not a good practice.
  • to add allowed_images=”*”, but the problem is that service tries to pull jupyterhub/singleuser image into my air-gapped machine without internet access

Is there a better way ?

Thanks!

2

allowed_images can be a callable

Which means you can make it a function that dynamically returns the list of images in any way you want.

1 Like
3

Thank you @manics !

Here is function that works for my case if anyone needs it:

def dynamic_allowed_images(spawner):
    """Return a list of available Docker image tags.

    Optionally filter by prefix via env var `ALLOWED_IMAGE_PREFIX`.
    Raises RuntimeError if no images match or discovery fails.
    """
    try:
        client = docker.from_env()
        prefix = os.environ.get("ALLOWED_IMAGE_PREFIX", "")

        tags = []
        for img in client.images.list():
            for tag in img.tags or []:
                if not prefix or tag.startswith(prefix):
                    tags.append(tag)
        unique_sorted = sorted(set(tags))
        if not unique_sorted:
            raise RuntimeError(
                "No Docker images found that match the configured prefix."
            )
        return unique_sorted
    except Exception as e:  # noqa: BLE001
        print(f"[JupyterHub] Error discovering Docker images: {e}", file=sys.stderr)
        raise
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