Settings.yaml

TYPO3:
  Flow:
    persistence:
      backendOptions:
        host: %PAAS_HOST%
        dbname: %PAAS_DB%
        user: %PAAS_USER%
        password: %PAAS_PASSWORD%

Web_Index.php

<?php

/*                                                                        *
 * This script belongs to the TYPO3 Flow framework.                       *
 *                                                                        *
 * It is free software; you can redistribute it and/or modify it under    *
 * the terms of the GNU Lesser General Public License, either version 3   *
 * of the License, or (at your option) any later version.                 *
 *                                                                        *
 * The TYPO3 project - inspiring people to share!                         *
 *                                                                        */

define('PAAS_HOST', $_SERVER["DB1_HOST"]);
define('PAAS_DB', $_SERVER["DB1_NAME"]);
define('PAAS_USER', $_SERVER["DB1_USER"]);
define('PAAS_PASSWORD', $_SERVER["DB1_PASS"]);

$rootPath = isset($_SERVER['FLOW_ROOTPATH']) ? $_SERVER['FLOW_ROOTPATH'] : FALSE;
if ($rootPath === FALSE && isset($_SERVER['REDIRECT_FLOW_ROOTPATH'])) {
  $rootPath = $_SERVER['REDIRECT_FLOW_ROOTPATH'];
}
if ($rootPath === FALSE) {
	$rootPath = dirname(__FILE__) . '/../';
} elseif (substr($rootPath, -1) !== '/') {
	$rootPath .= '/';
}

require($rootPath . 'Packages/Framework/TYPO3.Flow/Classes/TYPO3/Flow/Core/Bootstrap.php');

$context = getenv('FLOW_CONTEXT') ?: (getenv('REDIRECT_FLOW_CONTEXT') ?: 'Development');
$bootstrap = new \TYPO3\Flow\Core\Bootstrap($context);
$bootstrap->run();

?>