[Unit]
Description=mastodon-backup
AssertFileIsExecutable=/home/mastodon/bin/mastodon-backup
Requires=mnt-mastodon.mount
After=mnt-mastodon.mount

[Service]
Type=oneshot
User=mastodon
Group=mastodon
ExecStart=/home/mastodon/bin/mastodon-backup

[Install]
WantedBy=multi-user.target