Phoenix app without mix phx.new generator

Let's start by creating our elixir app

mix new web

And then install phoenix, plug_cowboy and jason package.

# mix.exs
defp deps do
  [
    {:phoenix, "~> 1.5.7"},
    {:plug_cowboy, "~> 2.0"},
    {:jason, "~> 1.2"}
  ]
end

Phoenix needs you to explicitly tell what json engine to use, so lets do that in the configs.

# configs.exs
config :phoenix, :json_library, Jason

Now we need to create our endpoint, which will be started in the applications' OTP.