Applications on Cloud Platform load a specific set of global configurations to ensure minimum basic operations are fulfilled. This configuration exists in your application’s settings.php file and looks similar to the following:

// On Cloud Platform, this include file configures Drupal to use the correct
        // database in each site environment (Dev, Stage, or Prod). To use this
        // settings.php for development on your local workstation, set $databases
        // (Drupal 7 or 9+) as described in comments above.
            if (file_exists('/var/www/site-php')) {
                require('/var/www/site-php/myapp/myapp-settings.inc');
            }

where myapp is the docroot of your website.

Ensure that you add the require line in your settings.php file. Otherwise, the system displays the following error:

The Settings file is not writable. The Drupal installer requires write permissions to ./sites/default/settings.php during the installation process. The webhosting issues documentation section offers help on this and other topics.

For example, by default, the config_sync_directory value is set to sites/default/files/config_xxxxx. To change this value, you must include the require line and add your custom line to override the system-defined value. The following code snippet shows how you can override the system-defined value for config_sync_directory with config directory above your docroot.

if (file_exists('/var/www/site-php')) {
           require '/var/www/site-php/' . $_ENV['AH_SITE_GROUP'] . '/' . $_ENV['AH_SITE_GROUP'] . '-settings.inc';
          }
$settings['config_sync_directory'] = $app_root . '/../config/' . basename($site_path);

The file added by the Acquia require line performs the following functions:

• Ensures that a valid version of Drupal core is installed.
• Determines what version of Drupal core is in use.
• Establishes the trusted host patterns for Drupal.
• Establishes the Memcached infrastructure and connection information.
• Builds all of the database connection information.
• Suppresses error reporting in the production environment.
• Sets the location of temporary files, including the Twig caches.