We'll need to have DebugKit included in the application file structure before we begin. There are a couple of ways to do this.

Git clone or submodule

If you use Git, you can create a clone of the code by executing the following command from your app/ directory on the command line:

$ git clone https://github.com/cakephp/debug_kit.git Plugin/DebugKit

If you already have your application under version control using Git, you can also add it as a submodule. Assuming that the base of your repository is the app/ folder, you would run the following command:

$ git submodule add https://github.com/cakephp/debug_kit.git app/Plugin/DebugKit

Using Composer

If you're using Composer as your dependency manager, you can simply include DebugKit as a plugin by adding the following code to your composer.json file:

{
  "require": {
    "cakephp/debug_kit": "2.2.*"
  }
}

After updating your composer.json file, simply update your application's dependencies using Composer.

Downloading files

An alternative method is to simply download the files and include them manually in your application from the following location:

https://github.com/cakephp/debug_kit/archive/master.zip

Perform the following steps:

When we call CakePlugin::load(), we request the framework to load the plugin by the given name, which also accepts an optional second argument, which is the configuration array for the plugin. We had already included the DebugKit/ directory in app/Plugin/, which is where plugins are located. You can change the location of where the plugins are loaded from using the path option in the plugin configuration array.

After loading the plugin, we included the Toolbar component in our AppController so it's available in all applications. This is a component included with the DebugKit plugin, which allows us to display a toolbar in the browser, thus providing a range of panels to introspect the application, the current request, SQL queries, and more. You'll notice that we included both the Session and Auth components here as well to propagate them in our application. The plugin itself is also extensible, allowing additional panels to be added. Once our plugin was loaded and the Toolbar component available, we made sure that the debug mode was enabled in our core.php file; we then navigated to the application in the browser to view the loaded toolbar.

Plugins may also load their own bootstrap.php and routes.php files to set up configurations and define routing settings. However, when a plugin is loaded, you must specify to load these configurations and settings. For example, if you had a Reports plugin that used these, you would load the plugin using the plugin configuration array as follows:

CakePlugin::load('Reports', array(
  'bootstrap' => true,
  'routes' => true
));

You can also load all plugins in your app/Plugin/ directory at once by calling CakePlugin::loadAll().