WP CDN or Local test

function cdnExternalOrLocal ($url) {
	$cdnIsUp = get_transient('cdn_is_up');
	$load_source;
	if ($cdnIsUp) {
		$load_source = 'external';
	} else {
		$cdn_response = wp_remote_get($url);
		if( is_wp_error( $cdn_response ) || wp_remote_retrieve_response_code($cdn_response) != '200' ) {
      $load_source = 'local';
    }
    else {
      $cdnIsUp = set_transient( 'cnd_is_up', true, MINUTE_IN_SECONDS * 20 );
      $load_source = 'external';
    }
	}
	return $load_source;
}