Good Luck, 'k?
This is a CTF that was used at CSAW CTF 2018. Participants were given main.py and an endpoint running the docker container.
If you'd like to try it yourself you can generate the docker container with the build-container.sh script and then run it with docker run --rm -p 5000:5000 csaw. This will give you a server running on port 5000 that you can query. Good luck!