Submission Username Customization

I use jupyterhub with a dockerspawner so that each jupyter notebook server is run in a separate container. All containers have a single user called jovyan so that when get_username() is called for submitting an assignment, it’s always jovyan. It would be nice if there was a way to change that. Jupyterhub deals with this with the user traitlet and dockerspawner has an environment variable (JPY_USER) set.

Any ideas?

[jhamrick]

The exchange directory has carefully crafted permissions to prevent students from accessing and modifying each others’ assignments. It’s not well document, but hopefully we won’t need such a complicated solution soon anyway 😄

Here’s the detailed explanation of how it works:

The toplevel exchange directory has 777 permissions, but the subdirectories have different permissions. The inbound directory is writable by all, but not readable or listable by anybody but the instructor. This has the effect that students can write to the directory in order to submit their assignments, but cannot see anybody else’s submissions. The outbound directory is readable by all but not writable by anybody but the instructor, so that only the instructor can release assignments:

$ ls -l /srv/nbgrader/exchange/cogsci131/
total 272
drwx-ws-wx 3968 instructor instructor 270336 Jan 17 04:22 inbound
drwxr-xr-x   21 instructor instructor   4096 Dec  5 16:56 outbound

Submission directories in the inbound directory are readable and writeable by everybody (though note because the inbound directory is not readable by anyone except the instructor, no one but the instructor can actually read or list these directories):

$ ls -l /srv/nbgrader/exchange/cogsci131/inbound/
total 15864
drwxrwxrwx 4 student1 instructor 4096 Dec 12 07:46 student1+final+2016-12-12 07:46:33 UTC

But the individual files within the submission directories are writable only by the student, which means that even if another student tried to remove the submission directory, they would not have permission to remove the files inside it:

$ ls -l /srv/nbgrader/exchange/cogsci131/inbound/student1+final+2016-12-12\ 07\:46\:33\ UTC/
total 524
-rw-r--r-- 1 student1 instructor   3946 Dec  5 16:56 0 - Index.ipynb
...

Released assignments are only writable by the instructor, but readable by everybody:

$ ls -l /srv/nbgrader/exchange/cogsci131/outbound/
total 76
drwxr-xr-x 4 instructor instructor 4096 Dec  5 10:23 final
$ ls -l /srv/nbgrader/exchange/cogsci131/outbound/final/
total 144
-rw-r--r-- 1 instructor instructor  3946 Dec  5 16:56 0 - Index.ipynb

[nthiery]

For reference: student id customization was implemented in #1098.