MySQL Issue

I'm new with OpenLS; so I went with fresh install of wordpress stack in parallel using OpenLS and Apache.
The stack is working and running normally using Apache but while access using OpenLS, the below error shown,

Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /home/wordpress/wp-includes/wp-db.php:1788 Stack trace: #0 /home/wordpress/wp-includes/wp-db.php(724): wpdb->db_connect() #1 /home/wordpress/wp-includes/load.php(561): wpdb->__construct('vShop', 'vZerro$7SQL', 'vShop', 'localhost') #2 /home/wordpress/wp-settings.php(124): require_wp_db() #3 /home/wordpress/wp-config.php(108): require_once('/home/wor...') #4 /home/wordpress/wp-load.php(50): require_once('/home/wor...') #5 /home/wordpress/wp-blog-header.php(13): require_once('/home/wor...') #6 /home/wordpress/index.php(17): require('/home/wor...') #7 {main} thrown in /home/wordpress/wp-includes/wp-db.php on line 1788

The above error when shown at wordpress installation wizard; so, I shifted to Apache to continue with the installation wizard; yet the same error repeats after install completion.

I'm running OpenLS as www-data:www-data and it working normally with different listeners (HTTP and HTPPS) using Example document root.
PHP info page shows lsphp80-mysql is enabled; please advise.