The api uses the ORM Prisma and it needs the MongoDB instance to be a replica set.
If you use MongoDB Atlas, the set is managed for you.
The simplest way to run a replica set locally is to use the docker-compose file in /tools. First disable any running MongoDB instance on your machine, then run the docker-compose file.
cd tools
docker compose up -d
During development and testing, the api exposes the endpoint GET auth/dev-callback. Calling this will log you in as the user with the email foo@bar.com
by setting the session cookie for that user.