Hi Christopher,
We're using docker-compose for both development and tests. We have a bunch of selenium specs that test our local modifications and they get run when we pull in instructure/stable to our fork. I've had a long-standing todo item to automate that and have our CI server watch instructure/stable, attempt the merge, and if it succeeds, run the specs in a container.
We're not using docker for production at the moment. Last I talked to Instructure about it (last summer) and they weren't quite there yet themselves. I'd like to get there eventually, but we don't currently have any of our production services in containers, so it would be a big step. We're moving to a new datacentre architecture "soon" and I'll finally have the ability to spin up VMs on my own and automate it, so I may start there and bring up new clusters when we do upgrades instead of keeping the same set of VMs chugging along forever like we do now. Eventually I could see that moving to containers, at least for the app servers.
Graham.