class myRepository
{
    private $conn;

    public function __construct(Connection $conn){
        $this->conn = $conn;
    }

    public function getStuff(){
        $sql = "SELECT * FROM stuff";
        return $this->conn->fetchAll($sql);
    }
}

services:
    my_repo:
    class: MyBundleRepositoryMyRepository
    arguments: ["@doctrine.dbal.default_connection"]

doctrine:
dbal:
    default_connection: default
    connections:
        default:
            driver:   pdo_mysql
            host:     "%database_host%"
            port:     "%database_port%"
            dbname:   "%database_name%"
            user:     "%database_user%"
            password: "%database_password%"
            charset:  UTF8

"doctrine/orm": "^2.5",
"doctrine/doctrine-bundle": "^1.6",