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A module (**not a plug**) for debugging in development.
This module is commonly used within a `Plug.Builder` or a `Plug.Router`
and it wraps the `call/2` function.
Notice `Plug.Debugger` *does not* catch errors, as errors should still
propagate so that 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.
**Note:** If this module is used with `Plug.ErrorHandler`, only one of
them will effectively handle errors. For this reason, it is recommended
that `Plug.Debugger` is used before `Plug.ErrorHandler` and only in
particular environments, like `:dev`.
defmodule MyApp do
if Mix.env == :dev do
use Plug.Debugger, otp_app: :my_app
def boom(conn, _) do
# Error raised here will be caught and displayed in a debug page
# complete with a stacktrace and other helpful info.
* `:otp_app` - the OTP application that is using Plug. This option is used
to filter stacktraces that belong only to the given application.
* `:style` - custom styles (see below)
## Custom styles
You may pass a `:style` option to customize the look of the HTML page.
use Plug.Debugger, style:
[primary: "#c0392b", logo: "data:image/png;base64,..."]
The following keys are available:
* `:primary` - primary color
* `:accent` - accent color
* `:logo` - logo URI, or `nil` to disable
The `:logo` is preferred to be a base64-encoded data URI so not to make any
external requests, though external URLs (eg, `https://...`) are supported.
## Links to the text editor
If a `PLUG_EDITOR` environment variable is set, `Plug.Debugger` will
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 (with the [TextMate](http://macromates.com) editor):