private static function checkPassword($pwd)
{
$errors = [];
if (strlen($pwd) < 8) {
$errors[] = 'Password too short!';
}
if (!preg_match('#[0-9]+#', $pwd)) {
$errors[] = 'Password must include at least one number!';
}
if (!preg_match('#[a-zA-Z]+#', $pwd)) {
$errors[] = 'Password must include at least one letter!';
}
if (count($errors) > 0) {
$msg = implode('<br/>', $errors);
\Yii::$app->session->addFlash('danger', "Application admin password from environment setting is not strong enough.<br/><i>{$msg}</i>");
}
}