add low-on-space notification

Containers/mastercontainer/cron.sh

@@ -57,6 +57,9 @@ while true; do
     # Remove dangling images
     sudo -u www-data docker image prune --force
 
+    # Check for available free space
+    sudo -u www-data php /var/www/docker-aio/php/src/Cron/CheckFreeDiskSpace.php
+
     # Remove mastercontainer from default bridge network
     if sudo -u www-data docker inspect nextcloud-aio-mastercontainer  --format "{{.NetworkSettings.Networks}}" | grep -q "bridge"; then
         sudo -u www-data docker network disconnect bridge nextcloud-aio-mastercontainer

php/src/Cron/CheckFreeDiskSpace.php

@@ -0,0 +1,26 @@
+<?php
+declare(strict_types=1);
+
+// increase memory limit to 2GB
+ini_set('memory_limit', '2048M');
+
+use DI\Container;
+use AIO\Data\DataConst;
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+$container = \AIO\DependencyInjection::GetContainer();
+
+/** @var \AIO\Docker\DockerActionManager $dockerActionManger */
+$dockerActionManger = $container->get(\AIO\Docker\DockerActionManager::class);
+/** @var \AIO\ContainerDefinitionFetcher $containerDefinitionFetcher */
+$containerDefinitionFetcher = $container->get(\AIO\ContainerDefinitionFetcher::class);
+
+$id = 'nextcloud-aio-nextcloud';
+$nextcloudContainer = $containerDefinitionFetcher->GetContainerById($id);
+
+$df = disk_free_space(DataConst::GetDataDirectory());
+if ($df !== false && (int)$df < 1024 * 1024 * 1024 * 5) {
+    error_log("The drive that hosts all docker volumes has less than 5 GB free space. Container updates and backups might not succeed due to that!");
+    $dockerActionManger->sendNotification($nextcloudContainer, 'Low on space!', 'The drive that hosts all docker volumes has less than 5 GB free space. Container updates and backups might not succeed due to that!');
+}