Loading ZendDeveloperTools Only in Development

I'm finally jumping feet first into ZF2 and one of the feature's I'm still not sure about is modules. Ideally, they break your code up into reusable chunks but it they still seem to have some drawbacks. For example, I'm a big fan of making sure a page is created as fast as possible (because performance is a feature) so I love the fact that there is a module (the ZendDeveloperTools module which I've mentioned before) that displays a bar at the bottom of the screen with various statistics about the page including how long it took to generate the page. The downside to the module system is that by enabling the module in the application.config.php file Zend will run code specific to that module even in environments where it won't ever be used (like production). Below is a simple fix to only load specific modules on your local instance.

Step 1 is to create an application.local.config.php file in your config directory with the contents listed below. In this case, this is only going to include the additional module that you want loaded but it could be expanded to include additional settings. Do not include this file in your version control system or it defeats the whole purpose of doing this. :-)

<?php
return array(
    'modules' => array(
        'ZendDeveloperTools',
    ),
);

This next step is where all the magic is going to happen. In your project's index.php file there is a line that normally looks like this:

Zend\Mvc\Application::init(require 'config/application.config.php')->run();

We're going to alter this so instead of just using the base application.config.php file we're going to load the base file and then merge in our changes using array_merge_recursive and then finally run the application.

// load the configuration
$config = require 'config/application.config.php';

// load the local config and merge
if(is_readable('config/application.config.local.php')){
    $localConfig = require 'config/application.config.local.php';
    $config = array_merge_recursive($config, $localConfig);
}

// Run the application!
Zend\Mvc\Application::init($config)->run();

At some point I need to look into caching this result but for small configs it shouldn't make that much of a difference.