Docker is cool way to deploy and use versioned application, but, IMVHO, it's only applicable for the case when you have single executable or single script, which sets up environment and invoke you for some particular functionality. Like run particular version of compiler for build scenario. Or run continious integration scenario. Or run web front-end environment.

1 function - 1 container with 1 interactive executable is easy to convert to Docker. But not Cache, which is inherently multi-process. Luca has done a great thing in his Docker container where he has wrappee whole environment (including control daemon, write daemon, journal daemon, etc) in 1 handy Docker container whith single entry point implemnted in Go as ccontainrmain but this is , hmm, ... not very effecient way to use Docker.

Containers is all about density of CPU/disk resources, and all the beauty of Docker is based upon the simplicity to run multiple user at the single host. Given this way of packing Cache' configuration to the single container (each user run whole set of Cache' control processes) you will get the worst scalability.

It would be much, much bettrer, if there would be 2 kinds of Cache' docker containers (ran via Swarm for example) where ther would be single control container, and multiple users containers (each connecting to their separate port and separate namespace). But, today, with current security implementation, there would be big, big problem - each user would be seeing whole configuration, which is kind of unexpected in the case of docker container hosting. 

Once, these security issues could be resolved there would be effeciet way to host Cache' under docker, but not before.