Here is my Pleroma Docker image: https://github.com/Angristan/dockerfiles/tree/master/pleroma
Features: not ran as root, uses Alpine, you can specify a commit
ALSO I've included the instructions to set up your instance with this image. We basically all have a similar image, but dropping a Dockerfile on you with elixir stuff in it doesn't help.
It's pretty easy and you have all you need int the README :blobthumbsup: