For only web, there is no need to build checkers.
There are so many checkers that will slow down make speed.
Also for some situations, users can build checkers without runners.
Without bundle, now you can choose to download single container.
For example, you can only download judger container to setup a new judger.
Also, the web container now no db and judger containing, except local sandbox.
You can use docker-compose to get every single container work together from now.
Single DB this time uses the latest MySQL 8 version, so some preferences are different.