self-hosting/roles/nextcloud-docker/templates/nextcloud/config/database.config.php

<?php
$CONFIG = array (
  'dbtype' => 'mysql',
  'dbname' => 'nextcloud',
  'dbhost' => 'db',
  'dbport' => '3306',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'nextcloud',
  'dbpassword' => '{{nextcloud_mysql_password}}',
);