WooCommerce Bootstrap Checkout Form

gistfile1.txt

add_filter('woocommerce_checkout_fields', 'addBootstrapToCheckoutFields' );
function addBootstrapToCheckoutFields($fields) {
    foreach ($fields as &$fieldset) {
        foreach ($fieldset as &$field) {
            // if you want to add the form-group class around the label and the input
            $field['class'][] = 'form-group'; 

            // add form-control to the actual input
            $field['input_class'][] = 'form-control';
        }
    }
    return $fields;
}