(I haven't looked at the code below)

Whenever I see big section-labels like this (especially if there are more than one) I usually take it as a sign that the class could benefit from a composition layer.  For example, make an actual "Dockercmd abstraction" class, and hang it off of this class as an attribute.  It goes a long way to help keep things organized and make use of the high-level class self-documenting (i.e. enhance readability).  It also helps a lot in unittesting b/c u can just mock the attribute reference.