adding notes on Nextcloud

services/nextcloud/readme.md

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+Nextcloud provides file sharing, calendaring, contact management, and other services (depending on the Nextcloud apps installed and enabled).
+
+See https://nextcloud.com/ for general information on Nextcloud.
+

services/nextcloud/upgrading.md

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+Steps to upgrade Nextcloud from one version to another.
+
+1.  Put the Nextcloud instance into maintenance mode
+    docker exec --user www-data nextcloud-app-1 php occ maintenance:mode --on
+
+    Note that 'docker exec' is used to run commands within the Nextcloud docker container; and '--user www-data' is used to run as the user that owns all of the Nextcloud files.
+
+2.  Back up the Nextcloud container's files to a location outside the container's mounted volume.  'rsync' is recommended:
+
+    rsync -Aavx /mnt/storage/appdata/nextcloud/www/ <backup-target-dir>/
+
+    rsync should be run as root.  rsync with these options should preserve file ownership & permissions
+
+3.  Back up MariaDB database:
+
+        docker exec nextcloud-db-container-name mysqldump --single-transaction -h localhost -u nextcloud_user -pnextcloud_password nextcloud_db_name > nextcloud-sqlbkp_$(date +"%Y%m%d").bak

services/readme.md

@@ -1 +1,2 @@
 This directory documents the services provided by various devices on the network.  There is one subdirectory per service provided.
+