Hi Jared,
I've not tried recently with the latest version, but previously I've had issues with applying the license to a docker image.
Joel and i tried a few things, but were unable to make the licence 'stick'.
What would happen is we would install the licence, the mango instance would restart, and in the logs it behaved as though the licence file wasn't created on disk.
Does it work fine with your Dockerfile above?
Cheers!
-Shaun