Set environment in wp-config.php file based on current URL

wp-config-set-environment.php

// ==============================================================================
// Set Current Environment
// ==============================================================================

/**
 * Define Environment/URL pairs for this project.
 *
 * Please include any possible URLs in each
 * environment as these will be checked against to set an environment constant
 * which can be easily used to create custom environment functionality and
 * configurations elsewhere in our application.
 *
 * Inspired by: http://selfteach.me/wordpress-multiple-environments/
 * Inspired by: https://deliciousbrains.com/updating-woocommerce/
 *
 * @author Christopher Hahn
 */
 $environments = array(

	'local' => [
		'localdevurl.local'
	],

	'staging' => [
		'staging.stagingurl.com',
	],

	'production'  => [
		'productionurl.com'
	]

);

// Get the current http host
$http_host = $_SERVER['HTTP_HOST'];

/**
* Loop over each of our environments, take a look at the environment array to
* see if a defined URL matches our HTTP_HOST, and then define our APP_ENVIRONMENT
* constant based on the results.
*
* @author Christopher Hahn
*/
foreach( $environments as $environment => $urls ) {

	if( array_search( $http_host, $urls ) !== false ){

		define( 'APP_ENVIRONMENT', $environment );

		break;

	}

}

/**
* If we get to this point and the environment is not yet defined, we are going to
* define our current environment as 'production' as a failsafe.
*
* @author Christopher Hahn
*/
defined( 'APP_ENVIRONMENT' ) or define( 'APP_ENVIRONMENT', 'production' );