Docker and z/VM or KVM?

At LinuxCon, KVM for z has been announced. From a Docker perspective, what does KVM change over a z/VM environment? There's a pretty short answer: nothing. KVM is cool for a number of things, z/VM is still king of the road, PR/SM still has got some bragging rights, and Docker doesn't care, as long as a Linux runs in it. Docker under both z/VM and KVM benefits from complementing technologies.

Closing Another Base Image Gap

Most recently, I mentioned (here and here) how to best deal with the fact that Ubuntu is widely used as base image, but does not exist on z Systems. A sufficiently close Debian is a decent solution for that.

Today's announcement at LinuxCon shows how this will get even easier: Ubuntu will be made available on z Systems. This will make all "FROM ubuntu" images no-brainers.

Image Decomposition

Looking at the swarm image we built previously, it's a couple of hundred MB in size -- for a small application. This image size will not slow down execution, since only files are touched which are needed when the application starts, but it will still be offending an aesthete's eye. Specifically for mainframers who have tried to save on every bit, because their core memory only had a couple of them (my knowledge is entirely anecdotal...). How can we kill that pain?