@title Using DarkConsole
@group developer

Enabling and using the built-in debugging console.

= Overview =

DarkConsole is a debugging console built into Phabricator which exposes
configuration, performance and error information. It can help you detect,
understand and resolve bugs and performance problems in Phabricator
applications.

DarkConsole was originally implemented as part of the Facebook Lite site; its
name is a bit of play on that (and a reference to the dark color palette its
design uses).

= Warning =

Because DarkConsole exposes some configuration and debugging information, it is
disabled by default (and **you should not enable it in production**). It has
some simple safeguards to prevent leaking credential information, but enabling
it in production may compromise the integrity of an install.

= Enabling DarkConsole =

You enable DarkConsole in your configuration, by setting `darkconsole.enabled`
to `true`, and then turning it on in `Settings` -> `Developer Settings`. Once
DarkConsole is enabled, you can show or hide it by pressing ##`## on your
keyboard.

Since the setting is not available to logged-out users, you can also set
`darkconsole.always-on` if you need to access DarkConsole on logged-out pages.

DarkConsole has a number of tabs, each of which is powered by a "plugin". You
can use them to access different debugging and performance features.

= Plugin: Error Log =

The "Error Log" plugin shows errors that occurred while generating the page,
similar to the httpd ##error.log##. You can send information to the error log
explicitly with the @{function@libphutil:phlog} function.

If errors occurred, a red dot will appear on the plugin tab.

= Plugin: Request =

The "Request" plugin shows information about the HTTP request the server
received, and the server itself.

= Plugin: Services =

The "Services" plugin lists calls a page made to external services, like
MySQL and the command line.

= Plugin: XHProf =

The "XHProf" plugin gives you access to the XHProf profiler. To use it, you need
to install the corresponding PHP plugin -- see instructions in the
@{article:Installation Guide}. Once it is installed, you can use XHProf to
profile the runtime performance of a page.