I believe this initially started with wanting to provide a core method of scaling processes on the same machine. #298 was the first attempt at this implementation but was not accepted as we let it sit around for too long. (I think)

Some questions come up in the new world of dokku that include things like zero-downtime checks and dockerfile deployments.

Issue/Question 1: Currently the zero-downtime checks rely on a web service being accessible for dokku to 'ping'. Therefore, if we run each Procfile entry in its own container things like workers can't be checked in this same manner.

There are two potential ways to go here. First would be to scale at the container level and somehow detect that a listener is running, then run checks. Otherwise, use the default container 'uptime' check we run when an app does not have a CHECKS file. The second method would be to use a similar pattern to the dokku-supervisor plugin and use a process manager in a single container to handle scaling.

Issue/Question 2: How should we scale dockerfile deployments.?
I don't use this method today and not sure I have a full grasp of implementation details. However, I think these can 'easily' be scaled using the multiple container approach.

refs: #733

ping @progrium @josegonzalez @joshco