PHP mysqli_connet 以localhost作为hostname 连接MySQL失败

初入Linux web服务器搭建，代码如下

<?php
$link=mysqli_connect('localhost','root','Ali123_123');
if(!$link){
echo "Error: Unable to connect to MySQL." . PHP_EOL;
echo "Debugging errorno: " . mysqli_connect_errno() . PHP_EOL;
echo "Debugging error: " . mysqli_connect_error() .PHP_EOL;
exit;
}

echo "Success: A proper connection to MySQL was made!" . PHP_EOL;
echo "Host information: " . mysqli_get_host_info($link) . PHP_EOL;

mysqli_close($link);
?>

CLI执行结果：

web访问结果：
Error: Unable to connect to MySQL. Debugging errorno: 2002 Debugging error: Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
php socket 配置：

MySQL socket 路径：

mysql root 权限：

为什么会有这种结果呢，该如何解决~
麻烦相助，多谢~

https://www.cnblogs.com/John-/p/6971160.html