Jupyterlab (Kubernetes) + Prodigy: "ERROR: Can't fetch project. Make sure the server is running correctly."

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1

Hello,

I have JupyterHub running in Kubernetes, and I would like to integrate the jupyterlab-prodigy plugin. In my JupyterHub setup each user's workspace is started in its own pod. I have configured the reverse proxy to forward all incoming requests on an endpoint of the form https://mydomain.com/prodigy/ to http://POD_IP:8080. However when I start the prodigy I get this error:

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I am able to get JSON responses when I query the /get_questions and /project endpoints.

I also read that this maybe caused by an outdated version of the murmurhash library but I am using 1.0.2 with prodigy 1.9.6, so I don't think that's the issue.

Any ideas?

2

Hi! This error happens on the very first request, so it's possible the problem is with the API/API access (since it starts and serves the app, but then can't make the request).

If you open your browser's developer tools, do you see a request error there? Maybe it's a CORS thing? Otherwise, is there any traceback in the terminal?

3

Hey Ines,

Thanks for the pointers. After looking at the console in Dev Tools I've discovered that the prodigy server is somehow reconstructing the url for the /project and /fonts endpoints. Basically the route I have configured in the proxy for the prodigy server is

https://jhub.mydomain.com/user/my_username/prodigy/ -> http://MY_POD_IP:8080

thus, in order to access the /project and /fonts endpoints, the URLs should look like:

https://jhub.mydomain.com/user/my_username/prodigy/project
https://jhub.mydomain.com/user/my_username/prodigy/fonts

however from the 404 errors in Dev Tools it looks like Prodigy is trying to access these endpoints at:

https://jhub.mydomain.com/hub/project
https://jhub.mydomain.com/hub/fonts

This actually makes sense. However, why is Prodigy loosing the URL prefix?

4

It seems like the /hub/ part of the URLs in my previous response just gets appended by the proxy when its doesn't have the route, so the Prodigy server is trying to query

https://jhub.mydomain.com/project
https://jhub.mydomain.com/fonts

completely dropping the prefix in the path. Hope this is helpful.

5

Yes, the path prefix is the problem here. We currently don't have a satisfying solution for modifying the paths, so subdomain-based routing is the easiest solution.

@honnibal explained this in more detail here: