So I ran into the Docker session “Better DevOps with MySQL and Docker” by Sunny Gleason from SunnyCloud late. Docker can help you lay down images of your system but it is not the be all end all for DevOps. Docker is a replacement for your Hypervisor. Docker instead is a way to isolate workloads on a single Operating system. You can run docker on top of a Hypervisor but it is not required.
Need to be careful with public images. Hard to tell the good from the bad. Docker working on a process to improve this. Some of the continuing issues are managing the connectivity between containers and the physical environment. Cross platform is also very new. Based on Linux containers so security is still an issue. Not really for multi tenant but for running multiple trusted solutions on the same hardware. Deployment can be I/O intensive.