Is there an officially sanctioned chef server Docker image?
There is not. Chef Server uses a number of pieces that don’t really cope well with Docker as a runtime environment. It could be done, but no one has put in the hours. If you want to go the Docker route, I would look at Goiardi instead as a starting point.
Actually, there is a really good one: https://github.com/3ofcoins/docker-chef-server
I am already using it in production in a smaller company with only about 100 Servers to manage. But it works quite well. The Docker image is hosted at quai.io and there also is a pull request with the changes needed for Chef Manage and the other plugins.