This describes how to setup a local judge system for the purpose of developing problems. For this you will need Docker and Docker Compose, as well as about a little over 3GB of disk space for the docker images. On Linux you will also have to enable cgroups (usually already active) and enable memory limits imposed by them (see this for how, it should be applicable for any system using Grub).
To start, run docker-compose up -d in this directory.
This will download the docker images and then start them in the background.
You follow the startup process using docker-compose logs -f.
Don't worry if the judge-web container is restarting repeatedly, it will do that until the database is reachable.
Once the web interface is reachable at http://localhost:8080/, run the ./setup-dev-settings.sh script.
If you are on Windows and don't have WSL or a Bash setup, just run the commands from the script manually, there is only two of them.
This will setup an account named test with password test for you, that can both submit solutions as well as access anything on the internal side of things.
It also creates a testing contest running indefinitely, and sets many settings you are used to from the main judge.
To shutdown the judge, run docker-compose down in this directory.
If you don't need the local setup anymore, you can reclaim disk space by deleting the docker images used for the judge.
To list installed docker images run docker image ls, and delete them using docker image rm.
You probably also want to delete the docker volume containing the database.
Find it with docker volume ls (it should be named local-judge_judge-db) and delete it with docker volume rm.