Different log level for different otp apps

config.exs

config :gnat, logger: [
  level: :info
]

logger.ex

defmodule Gnat.Stream.Logger do
  use Gnat.Logging, otp_app: :gnat
end

logging.ex

defmodule Gnat.Logging do

  defmacro __using__(options) do
    quote bind_quoted: [otp_app: options[:otp_app]] do
      require Logger

      def debug(message, metadata \\ []), do: log(:debug, message, metadata)
      def info(message,  metadata \\ []), do: log(:info,  message, metadata)
      def warn(message,  metadata \\ []), do: log(:warn,  message, metadata)
      def error(message, metadata \\ []), do: log(:error, message, metadata)

      @otp_app otp_app

      def log(level, message, metadata \\ []) do
        config = Application.get_env(@otp_app, :logger, [])
        config_level = Keyword.get(config, :level, :debug)
        if level_to_int(config_level) <= level_to_int(level) do
          Logger.log(level, message, metadata)
        end
      end

      defp level_to_int(:debug), do: 0
      defp level_to_int(:info),  do: 1
      defp level_to_int(:warn),  do: 2
      defp level_to_int(:error), do: 3
    end
  end

end