Optimized auto backup

roles/independent_backup-to-usb/templates/99-usbstick.rules.j2

@@ -1 +0,0 @@
-ACTION=="add", SUBSYSTEM=="block", ENV{ID_SERIAL_SHORT}=="{{ backup_to_usb_serial_short }}", RUN+="/usr/bin/systemd-mount --no-block $devnode {{ mount_point }}", SYMLINK+="backup_usb"

roles/independent_backup-to-usb/templates/backup-to-usb.service.j2

@@ -1,10 +1,13 @@
 [Unit]
-Description=Backup to USB when it's plugged in
-After=local-fs.target
+Description=Backup to USB when mounted to {{ backup_to_usb_mount }}
+Wants={{systemctl_mount_service_name}}
+After={{systemctl_mount_service_name}}
 OnFailure=systemd-email@%n.service
+Requires=backups-cleanup.service
+After=backups-cleanup.service
 
 [Service]
-ExecStart={{ backup_to_usb_script_path }} {{ mount_point }}/{{ backup_to_usb_subdirectory }} {{ backup_to_usb_source_path }}
+ExecStart=/bin/python {{ backup_to_usb_script_path }} {{backup_to_usb_source}} {{backup_to_usb_destination}}
 
 [Install]
-WantedBy=multi-user.target
+WantedBy=multi-user.target

roles/independent_backup-to-usb/templates/backup-to-usb.sh.j2

@@ -1,35 +0,0 @@
-#!/bin/sh
-backup_to_usb_destination_path="{{ mount_point }}" &&
-echo "backup to usb destination path: $backup_to_usb_destination_path" &&
-
-source_path="{{ backup_to_usb_source_path }}" &&
-echo "source path: $source_path" || exit 1
-
-if [ ! -d "$backup_to_usb_destination_path" ]; then
-    echo "Directory $backup_to_usb_destination_path does not exist" &&
-    exit 1
-fi
-
-machine_id="$(sha256sum /etc/machine-id | head -c 64 )" &&
-echo "machine id: $machine_id" &&
-
-versions_path="$backup_to_usb_destination_path$machine_id/backup-to-usb/" &&
-echo "versions path: $versions_path" || exit 1
-
-if [ ! -d "$versions_path" ]; then
-    echo "Creating $versions_path..." &&
-    mkdir -vp $versions_path || exit 1
-fi 
-
-previous_version_path="$(ls -d $versions_path* | tail -1)" &&
-echo "previous versions path: $previous_version_path" &&
-
-current_version_path="$versions_path$(date '+%Y%m%d%H%M%S')" &&
-echo "current versions path: $current_version_path" &&
-
-echo "creating backup destination folder..." &&
-mkdir -vp "$current_version_path" &&
-
-echo "Starting synchronization..."
-rsync -abP --delete --delete-excluded --link-dest="$previous_version_path" "$source_path" "$current_version_path" &&
-echo "Synchronization finished." || exit 1