As to the last point about the error.
Try merging pull request #882 (from taniwallach)
into your copy of webwork2
Then rebuild the software inside the docker again.
You might have to delete stale images to make sure that
docker rebuilds from scratch.
1. At the moment there isn't another version of the docker environment using alternative operating systems but I encourage people to develop something like this.
2. I wouldn't use the docker version of this in production just yet -- we are still refining it. In the long run yes -- Pan Luo (@xcompass) says that they are planning to run WeBWorK at UBC from a docker environment. You can check with @xcompass if you want to find the lastest news on using docker and webwork in production.
3. Your courses are in a file webwork2/.data/courses and can be accessed from "outside" the docker environment. The course files don't include the database information however.
You need to archive your course on it's current server, transfer the archived .tar.gz file to webwork2/.data/courses, then start up the container (docker-compose up) and from the admin page for the site unarchive the course which you have placed in webwork2/.data/courses