Form builder; Configure the site's maintenance status.
system_site_maintenance_mode_submit()
function system_site_maintenance_mode($form, &$form_state) {
$config = config('system.maintenance');
$form['maintenance_mode'] = array(
'#type' => 'checkbox',
'#title' => t('Put site into maintenance mode'),
'#default_value' => $config
->get('enabled'),
'#description' => t('Visitors will only see the maintenance mode message. Only users with the "Access site in maintenance mode" <a href="@permissions-url">permission</a> will be able to access the site. Authorized users can log in directly via the <a href="@user-login">user login</a> page.', array(
'@permissions-url' => url('admin/config/people/permissions'),
'@user-login' => url('user'),
)),
);
$form['maintenance_mode_message'] = array(
'#type' => 'textarea',
'#title' => t('Message to display when in maintenance mode'),
'#default_value' => $config
->get('message'),
);
return system_config_form($form, $form_state);
}