Binderhub: Preview from nbviewer while loading Binder shows 404 when giving a notebook-file path

[labarba]

I noticed that when I have created a Binder button that points to a particular notebook in the repository—i.e., I have provided the optional path to a notebook file in https://mybinder.org—the preview shows an ugly 404 while loading. The notebook eventually loads, but if the user is impatient, they may give up in response to the error message. See screenshots below.

Normal view when launching:

---

View when launching with a path to notebook file:

[labarba]

Here are the launch links, in each case:

https://mybinder.org/v2/gh/engineersCode/EngComp1_offtheground/master

https://mybinder.org/v2/gh/engineersCode/EngComp1_offtheground/master?filepath=%2Fnotebooks_en%2F2_Jupyter_strings_and_lists.ipynb

[betatim]

https://mybinder.org/v2/gh/engineersCode/EngComp1_offtheground/master?filepath=notebooks_en%2F2_Jupyter_strings_and_lists.ipynb works. Note that there is no %2F at the start of the filepath.

How did you generate the link?

[labarba]

Hmm. I entered the file path where it says "Path to a notebook file (optional)" on the My Binder form: /notebooks_en/2_Jupyter_strings_and_lists.ipynb

With that file path, the notebook _does_ open when I click the orange "Launch" button right next to it. And the notebook _does_ open after a while when clicking the binder button, but we see the 404 message while launching.

Entering notebooks_en/2_Jupyter_strings_and_lists.ipynb instead fixes it, yes. Thank you.

[betatim]

Thanks! Good to hear that it now works. I think we should think about updating the logic in our form to remove a leading / if it is there as it is most likely a mistake by the user.

[choldgraf]

Perhaps we should re-purpose this issue (or close this and open a new one) about the / problem?

[labarba]

Not sure how to state the new issue: those of you who know the code can express it better. From my perspective, it should work whether the user adds or leaves out the /.

[willingc]

@labarba Agreed.

@betatim @choldgraf Let's open an issue if not already open to strip the leading / if typed by user.

[choldgraf]

@labarba thanks for bringing this to our attention!!! Looks like we've now got #622 to deal with the specific technical bug that you found! Just FYI :-)