Heroku

Install heroku toolbelt

Install heroku-toolbelt by package manager or download it from https://toolbelt.heroku.com.

Add Elixir support for heroku app

Set buildpack for your elixir app and create a elixir_buildpack.config file in your app's root dir.

Change elixir app config

Set http port to {:system, "PORT"} to listen port by system environment.

setting up env-backed port

config :maru, YourAPI,
  http: [port: {:system, "PORT"}]

Push your code to heroku

Push your app to heroku by git github or dropbox.