Magento 2 Database Configuration file

app/etc/env.php is the database configuration file for magento2

'db' =>
  array (
    'table_prefix' => '',
    'connection' =>
    array (
      'default' =>
      array (
        'host' => 'localhost',
        'dbname' => 'database_name',
        'username' => 'database_username',
        'password' => 'database_password',
        'active' => '1',
      ),
    ),
  ),