I am not sure how you define 2015-class, but building a release with distillery, and running docker build on a Dockerfile that copies the tarball (that includes everything needed to run your app (ERTS, app code, NIFs, etc)) makes a docker container that you can deploy as you'd expect. If you want to use clustering it's a bit more setup, but I was able to get a simple phoenix app running clustered on Google Container Engine (Kubernetes) in about 4-5 hours, starting with zero knowledge about Kubernetes or Elixir deployment. I pushed my code to github[1], and I did a talk on it at our local Elixir meetup[2].

Now that I have it figured out it's totally painless to upgrade, especially because of the Kubernetes tools. Simply make a new release, build a new container, push it to your docker registry, and then do a rolling update with kubernetes using the new version of the container. You can also add/remove scale on the fly, libcluster handles it all.

[1]https://github.com/bbhoss/k8sexamplephx

[2]https://www.youtube.com/watch?v=SNll1r6ZtO0&feature=youtu.be...