wp-config DB_HOST for staging & production on same server

I’m trying to set up my staging and production areas on one server. Needless to say, it’s not working on staging – Database Connection error. Works on local! So I’m using the wrong host name or something. Running EC2. How do i differentiate the host names / server name for staging and production using the same server?

$environments = array(
    'development' => 'radpress.dev',
    'staging' => '**?????????????????????????**',
    'production' => '**??????????????**',
);
// Get Server name
$server_name = $_SERVER['SERVER_NAME'];

foreach($environments AS $key => $env){
    if(strstr($server_name, $env)){
        define('ENVIRONMENT', $key);
        break;
    }
}

// If no environment is set default to production
if(!defined('ENVIRONMENT')) define('ENVIRONMENT', 'production');

// Define different DB connection details depending on environment
switch(ENVIRONMENT){

    case 'development':

        define('DB_NAME', 'radpress.dev');
        define('DB_USER', 'lookrad');
        define('DB_PASSWORD', '');
        define('DB_HOST', 'localhost');
        define('WP_SITEURL', 'THIS WORKS');
        define('WP_HOME', 'THIS WORKS');
        define('WP_DEBUG', true);
        define('WP_CACHE', false );
        break;

    case 'staging':

        define('DB_NAME', 'radpress.staging');
        define('DB_USER', 'lookrad');
        define('DB_PASSWORD', '');
        define('DB_HOST', '??? IS THIS JUST THE HOSTNAME? ??');
        define('DB_CHARSET', 'utf8');
    define('DB_COLLATE', 'utf8_unicode_ci');
        define('WP_SITEURL', 'IS THIS JUST THE PATH?? OR JUST THE SERVER NAME?' );
    define('WP_HOME', 'IS THIS JUST THE PATH?? OR JUST THE SERVER NAME?' );
    define('WP_DEBUG', TRUE );
    define( 'WP_CACHE', TRUE );
        break;

    case 'production':

        define('DB_NAME', 'radpress.production');
        define('DB_USER', 'DBUSER');
        define('DB_PASSWORD', 'PASSWORD');
        define('DB_HOST', '127.0.0.1');
        define('DB_CHARSET', 'utf8');
    define('DB_COLLATE', 'utf8_unicode_ci');
        define('WP_SITEURL', '');
        define('WP_HOME', ');
        define('WP_DEBUG', false);
        define('WP_CACHE', TRUE );
        break;
}