Get link by page template name

get-link-by-page-template-name.php

<?php
/**
 * Retrieve the URL of the page using a template.
 *
 * @author Lauren Levin (Pittenger)
 *
 * @param string $template_name The name of the page template, ex. 'page-templates/countries.php'.
 */
function get_link_by_page_template_name( $template_name ) {
	$url   = null;
	$pages = get_pages(
		array(
			'meta_key'   => '_wp_page_template',
			'meta_value' => $template_name,
		)
	);
	if ( isset( $pages[0] ) ) {
		$url = get_page_link( $pages[0]->ID );
	}
	return $url;
}