[i_have_to_speak]

In your Jenkins example, why use docker? Why not ask the devs to directly install Jenkins on their box?

[zwischenzug]

Because the builds would not be contained. There were many dependencies that needed to be installed on each box.

Using Docker meant that the slaves could be built from scratch as well.

See here: http://zwischenzugs.tk/index.php/2014/11/08/taming-slaves-wi...