Autograder Wrapper for Gradescope

This is the result of following this tutorial:

https://gradescope-autograders.readthedocs.io/en/latest/git_pull/

It is a massively helpful upfront step that will save hours of effort later on when iterating on grading scripts.

The key idea is that for each PA, Gradescope wants you to upload a zip file that has a setup.sh script that installs dependencies (like Java or valgrind or whatever you need). This actually takes a while to run, so you don't want to be iterating on a grading script by re-uploading this script over and over. This wrapper script installs dependencies once, and then on each student submission, will fetch the appropriate grading repository for the PA and run the script specific to that repo.

(My) Setup

• [Optional] Make a new Github organization for your course. You can also just host the repositories yourself, but it's pretty easy to get Github to give you unlimited private repositories for a course, which I do literally every quarter:

https://education.github.com/discount_requests/new

• [Optional] Make a new Github account just for your course. You can use your own account, but for general security hygeine's sake it's better to make a new one. Since we will make a separate repository for each PA's grading scripts, it's best to follow the instructions for "Machine Users":

https://developer.github.com/v3/guides/managing-deploy-keys/#machine-users

• Use the account settings in Github and ssh-keygen to make a password-less key pair. Save the private key somewhere on the machine you use to do development (this avoids checking it into a repository anywhere).

• Edit setup.sh in this repo to add any packages or dependencies you need. That script run with root and internet access, so you have a ton of control.

• Edit run_autograder in this repo to point to the organization you're using. In the example it says

  git clone [email protected]:ucsd-cse12-w17/${ASSIGNMENT_TITLE}-grading.git
  

  The ucsd-cse12-w17 is what I named the course organization. If you're using your own private repos, that will be your username.

  I also picked the convention that all of my grading scripts would be separate repositories named paN-grading. This name is important, because ASSIGNMENT_TITLE is an environment variable set by Gradescope. So I made Gradescope assignments called pa2, pa3, and so on, and then made Github repositories for grading them with the same name and -grading appended. The nice thing about this is that it meant I can do this setup once and then upload the same configuration for each PA.

  The other convention I picked is that each grading repo has a grade script at

  ${ASSIGNMENT_TITLE}-grading/ucsd-cse12-${ASSIGNMENT_TITLE}-grading/grade
  

  This isn't strictly necessary, actually. It just helped keep things clean when there were multiple directories in the grader itself, and it would be known that the ucsd-cse12-pa2-grading subdirectory would hold the grading script itself.

• Run

  bash build-for-gradescope.sh PATH_TO_PRIVATE_KEY
  

  This will create a file called pa.zip which is suitable for uploading to Gradescope's autograder page. On each submission, it will clone the appropriate paN-grading repo based on the title of the submission, and run the grade script in that repo. The grade script must put a JSON file into

  /autograder/results/results.json

  and it gets to assume that student code will be in /autograder/submission/.

  (This is per https://gradescope-autograders.readthedocs.io/en/latest/specs/)