logger.ex

defmodule Saturn.Logger do
  use Timex
  require Logger
  alias Plug.Conn
  @behaviour Plug

  def init(opts) do
    Keyword.get(opts, :log, :info)
  end

  def call(conn, level) do
    time = Date.now |> Date.universal |> DateFormat.format! "{ISOz}"
    before_time = :erlang.now
    Logger.metadata(request_id: request_id)

    conn
    |> Conn.register_before_send(fn conn ->
      Logger.log level, fn ->
        after_time = :erlang.now
        diff = :timer.now_diff(after_time, before_time)
        Logfmt.encode [time: time,
          method: conn.method,
          path: Conn.full_path(conn),
          status: conn.status,
          elapsed: "#{diff / 1000}ms"]
      end
      conn
    end)
  end
end