codice:
+ docker-compose up --build -d
blablabla...
Successfully built 3f4e3ce63670
Successfully tagged test-image:latest
Starting tmphbzh6gzgcy_redis_1 ... 
Starting tmphbzh6gzgcy_redis_1 ... done
Recreating tmphbzh6gzgcy_app_1 ... done

+ cat test.php
<?php
$pdo = new PDO(
    "mysql:host=127.0.0.1;dbname=test",
    'root', 'root2'
);

$query = $pdo->query("SELECT * FROM people");
var_dump($pdo->errorInfo());

foreach($query as $row ){  
    var_dump($row);  
}  
+ docker run test-image php /usr/local/bin/test.php

Fatal error: Uncaught PDOException: SQLSTATE[HY000] [2002] Connection refused in /usr/local/bin/test.php:5
Stack trace:
#0 /usr/local/bin/test.php(5): PDO->__construct('mysql:host=127....', 'root', 'root2')
#1 {main}
  thrown in /usr/local/bin/test.php on line 5
rino@comex:/mnt/storage/pending/tmp.HBZh6gzGcY$
Ancora non ci siamo.
Nel frattempo, che differenza c'è tra MYSQL_PASSWORD e MYSQL_ROOT_PASSWORD?