Adding Ecto To An Elixir Application Without Phoenix

application.ex

defmodule MyApp.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application

  def start(_type, _args) do
    # List all child processes to be supervised
    children = [
      MyApp.Repo,
      MyApp.OtherRepo
    ]

    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: MyApp.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

config.exs

# This file is responsible for configuring your application
# and its dependencies with the aid of the Mix.Config module.
use Mix.Config

# This configuration is loaded before any dependency and is restricted
# to this project. If another project depends on this project, this
# file won't be loaded nor affect the parent project. For this reason,
# if you want to provide default values for your application for
# third-party users, it should be done in your "mix.exs" file.

# You can configure your application as:
#
#     config :my_app, key: :value
#
# and access this configuration in your application as:
#
#     Application.get_env(:my_app, :key)
#
# You can also configure a third-party app:
#
#     config :logger, level: :info
#

config :my_app, MyApp.Repo,
	database: "ecto1",
	username: "developer",
	password: "",
	hostname: "localhost"

config :my_app, MyApp.OtherRepo,
  database: "ecto2",
  username: "developer",
  password: "",
  hostname: "localhost"

config :my_app, :ecto_repos, [MyApp.Repo, MyApp.OtherRepo]

# It is also possible to import configuration files, relative to this
# directory. For example, you can emulate configuration per environment
# by uncommenting the line below and defining dev.exs, test.exs and such.
# Configuration from the imported file will override the ones defined
# here (which is why it is important to import them last).
#
#     import_config "#{Mix.env()}.exs"

mix.exs

defmodule MyApp.MixProject do
  use Mix.Project

  def project do
    [
      app: :my_app,
      version: "0.1.0",
      elixir: "~> 1.8",
      start_permanent: Mix.env() == :prod,
      deps: deps()
    ]
  end

  # Run "mix help compile.app" to learn about applications.
  def application do
    [
      extra_applications: [:logger],
      mod: {MyApp.Application, []}
    ]
  end

  # Run "mix help deps" to learn about dependencies.
  defp deps do
    [
      {:postgrex, "~> 0.14.1"},
      {:ecto_sql, "~> 3.0"}
    ]
  end
end

other_repo.ex

defmodule MyApp.OtherRepo do
	use Ecto.Repo,
    otp_app: :my_app,
    adapter: Ecto.Adapters.Postgres
end

repo.ex

defmodule MyApp.Repo do
	use Ecto.Repo,
    otp_app: :my_app,
    adapter: Ecto.Adapters.Postgres
end