Hello, I am a beginner in Elixir/Phoenix and I am having a look at your project for learning purposes.

I want to create/migrate the database but I have an error:
$ mix ecto.create

** (RuntimeError) connect raised KeyError exception: key :username not found.

One can quickly see that there are missing parameters specifying username/password:
https://github.com/thoughtbot/constable/blob/master/config/dev.exs#L41

How does it work? Where does it get the credentials from? I guess I'm not supposed to add options myself by editing the code?

Thank you for any help!