Discussing the modern implementations of containers, like Docker, rkt, and LXC. Things like jails have been time-tested and most of the complaints in the post aren't applicable to them. "Container" has taken on new meaning to mean such new-fangled container frameworks. IMO calling something like a jail a container is now obtuse and incorrect.

My post was primarily referring to Docker, as you can tell from the grandparent that says "Docker and database do not mix", and then the rest of the post body that speaks to Docker-specific issues.