@dimitarvp is right, there’s no tight coupling so you should be able to get Pow working without Ecto or a DB. There are several ways to do it, but I would just set up a custom context and user module.

This is also how I unit test Pow so I’m not relying on Ecto/DB. The user module is necessary because it’s used to generate a changeset for the form, and to fetch the user id field dynamically for the form. Depending how your app works, you could also use the the user module to load the password from the TOML file on compile.

config :my_app, :pow,
  user: MyApp.Users.User,
  users_context: MyApp.Users

defmodule MyApp.Users.User do
  defstruct email: nil, password_hash: nil

  use Pow.Ecto.Schema

  def changeset(user, _params), do: user

  def verify_password(user, password), do: # Verify password here
end

defmodule MyApp.Users do
  use Pow.Ecto.Context

  def authenticate(_params), do: # Use params to look up user and verify password with `MyApp.Users.User.verify_password/2`

  def create(_params), do: {:error, :not_implemented}

  def update(_user, _params), do: {:error, :not_implemented}

  def delete(_user), do: {:error, :not_implemented}

  def get_by(_clauses), do: {:error, :not_implemented}
end

I imagine that since you use TOML files there will be no user create/update/delete, but only authentication. In that case, you should ensure that there is only the session controller. You can take a look at the context callbacks for specs.

You are the first person I’ve heard from that wants to use Pow in this way. I built Pow so it’s easy to decouple any group of modules (Ecto, Phoenix, Plug), but I would love to hear how it works in practice and if there’s something that can be improved. Please don’t hesitate to open any issues or PR on github

Quick update: I just released 1.0.8 today where there is no longer an expectation that @changeset is an Ecto.Changeset struct. This should make it easier for you to use Pow without Ecto

Haven’t looked into most of Pow’s guts but I’d guess it’s not tightly related to a RDBMS; only to Ecto.

So if you find – or invent – a way to access those files through an Ecto interface then I’d expect Pow to work just fine after.