Its impossible to connect to Planetscale cloud Mysql DB from PHP. I try with mysqli doing :
$hostname = "secret";
                $dbName = "secret";
                $port = "3306";
                $ssl = "/etc/ssl/certs/ca-certificates.crt";
                $user="secret";
                $passs="pscale_pw_xxx";
                $mysqli = mysqli_init();
                $mysqli->ssl_set(NULL, NULL, $ssl, NULL, NULL);
                $mysqli->real_connect($hostname,$user, $passs, $dbName, $port);
                if ($mysqli->connect_error) {
                    echo 'not connected to the database';
                } else {
                    echo "Connected successfully";
                    $mysqli->query("create table test(TOTO text)");
                }
i have bad messages : "
Warning:  mysqli::real_connect(): this stream does not support SSL"
and message like "
Warning:  mysqli::real_connect(): Cannot connect to MySQL by using SSL" and also "
Warning:  mysqli::query(): invalid object or resource mysqli"
etc...
I have tried PDO solution with no sucess at all, my code below
  
  
  function Connect_Planet($HOST, $LOGIN, $PASS, $DB_NAME)
  {
      
      
        try {
            
            $dsn = 'mysql:host=' . $HOST . ';dbname=' . $DB_NAME;
            $user = "";
            $dbP = "";
            $options = array(
                1009 => "/etc/ssl/certs/ca-certificates.crt",
                1014 => false,
                PDO::MYSQL_ATTR_SSL_CA => "/etc/ssl/certs/ca-certificates.crt"
            );
            
          
                                    
            $this->CONN = new PDO($dsn, $LOGIN, $PASS,$options);
            $this->CONN->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
       
        } catch(PDOException $e) {
            
            $this->MSG= $e->getMessage();
             $this->IS_OPEN=0;
            return 0;
        }
        
            $this->VAR_HOST=$HOST;
            $this->VAR_LOGIN=$LOGIN;
            $this->VAR_PASS=$PASS;
            $this->VAR_DBNAME=$DB_NAME;
            $this->IS_OPEN=1;
            
          return 1;   
         
                     
  }
  
   
If someone have succeed with php and planetscale database working fine, please let me know how u did it. Thanks in advance,