source: astra/1.1.5/sidebar.php

<?php
/**
 * The sidebar containing the main widget area.
 *
 * @link https://developer.wordpress.org/themes/basics/template-files/#template-partials
 *
 * @package Astra
 * @since 1.0.0
 */

$sidebar = apply_filters( 'astra_get_sidebar', 'sidebar-1' );

?>

<div itemtype="http://schema.org/WPSideBar" itemscope="itemscope" id="secondary" <?php astra_secondary_class(); ?> role="complementary">

        <div class="sidebar-main">

                <?php astra_sidebars_before(); ?>

                <?php if ( is_active_sidebar( $sidebar ) ) : ?>

                        <?php dynamic_sidebar( $sidebar ); ?>

                <?php endif; ?>

                <?php astra_sidebars_after(); ?>

        </div><!-- .sidebar-main -->
</div><!-- #secondary -->