Thank you!
Yes, and as a matter of fact this is how mix phx.new --umbrella will construct your application for you. The super-brief explanation is that you want to have only one umbrella application directly responsible for your Ecto interactions with a given Repo. You have that umbrella app provide an abstraction layer used by your other applications within the umbrella, and they depend on that first one in their mix.exs. This is mostly just a slight variation on Phoenix Contexts which were introduced in Phoenix 1.3 - the umbrella structure just sort of forces your hand a little bit in terms of providing good isolation/boundaries.
