WordPress Configuration for Multiple Environments

wp-config.php

<?php

// Dynamically Set Environment Variables
	$server[] = $_SERVER['HTTP_HOST'];
	$server[] = $_SERVER['LOCAL_NAME'];

	$environment->local[] = 'example.dev';
	$environment->staging[] = 'staging.example.com';

	if ( array_intersect( $environment->local, $server ) ) {
		// Local Development
		$db_hostname = '127.0.0.1';
		$db_username = 'username';
		$db_password = 'password';
		$db_database = 'database';

		define( 'WP_DEBUG', true );

	} elseif ( array_intersect( $environment->staging, $server ) ) {
		// QA Staging
		$db_hostname = 'localhost';
		$db_username = 'username';
		$db_password = 'password';
		$db_database = 'database';

	} else {
		// Production Environment
		$db_hostname = '';
		$db_username = '';
		$db_password = '';
		$db_database = '';

	}

// Configure MySQL Database Settings
	define( 'DB_NAME', $db_database );
	define( 'DB_USER', $db_username );
	define( 'DB_PASSWORD', $db_password );
	define( 'DB_HOST', $db_hostname );
	define( 'DB_CHARSET', 'utf8' );
	define( 'DB_COLLATE', '' );

// Wordpress Application Options + Settings
// http://codex.wordpress.org/Editing_wp-config.php

	$table_prefix  = 'wp_';

	// http://codex.wordpress.org/Editing_wp-config.php#Security_Keys
	define( 'AUTH_KEY',         'put your unique phrase here' );
	define( 'SECURE_AUTH_KEY',  'put your unique phrase here' );
	define( 'LOGGED_IN_KEY',    'put your unique phrase here' );
	define( 'NONCE_KEY',        'put your unique phrase here' );
	define( 'AUTH_SALT',        'put your unique phrase here' );
	define( 'SECURE_AUTH_SALT', 'put your unique phrase here' );
	define( 'LOGGED_IN_SALT',   'put your unique phrase here' );
	define( 'NONCE_SALT',       'put your unique phrase here' );

	define( 'WP_MEMORY_LIMIT', '128M' );
	define( 'AUTOSAVE_INTERVAL', 300 );
	define( 'WP_POST_REVISIONS', false );

	define( 'WP_HOME',    'http://' . $_SERVER['HTTP_HOST'] );
	define( 'WP_SITEURL', 'http://' . $_SERVER['HTTP_HOST'] );

	define( 'DISALLOW_FILE_EDIT', true );
	define( 'DISALLOW_FILE_MODS', true );

	define( 'ABSPATH', dirname(__FILE__) . '/' );
	require_once( ABSPATH . 'wp-settings.php' );

?>