It will automatically setup a default Procfile to run:
_build/prod/rel/<your app name>/bin/<your app name> start
You would use this if you are currently using both Elixir and Phoenix buildpacks and you want to use releases. If you are not using the Phoenix buildpack this could also be useful but there is a PR open to support releases in the Elixir buildpack directly that you might want to keep an eye on.
Why you might use releases vs
mix run phx.server is covered in these links:
The tldr is it avoids latency spikes caused by lazily loading the code after the app starts.
mix release --overwrite
There's no configuration as yet. If you have need please send a PR or open an issue. I'm not going to have a lot of time for maintenance on this so make no guarantees on response times. That said please open a PR/issue if there's something you think is useful so I can gauge interest.
Copy the snippet above into CLI.