Plug.Debugger

A module (not a plug) for debugging in development.

The module is commonly used within a Plug.Builder or a Plug.Router and it wraps the call/2 function:

defmodule MyApp do
  use Plug.Builder

  if Mix.env == :dev do
    use Plug.Debugger, otp_app: :my_app
  end

  plug :boom

  def boom(conn, _) do
    # Error raised here will be caught and displayed in a debug
    # page complete with a stacktrace and other helpful info
    raise "oops"
  end
end

Notice Plug.Debugger does not catch errors, as errors should still propagate so the Elixir process finishes with the proper reason. This module does not perform any logging either, as all logging is done by the web server handler.

PLUG_EDITOR

If a PLUGEDITOR environment variable is set, Plug.Debugger is going to use it to generate links to your text editor. The variable should be set with FILE and _LINE placeholders which will be correctly replaced, for example:

txmt://open/?url=file://__FILE__&line=__LINE__

Manual usage

One can also manually use Plug.Debugger by invoking the wrap/3 function directly.