# cat /etc/systemd/system/restart-prosody.service 
[Unit] 
Description=restart prosody 
Requisite=prosody.service 

[Service] 
Type=oneshot 
ExecStart=/bin/systemctl restart prosody.service 

# cat /etc/systemd/system/restart-prosody.timer 
[Unit] 
Description=reload prosody once a month, otherwise https certificate may get old and prosody won't reload it automatically 

[Timer] 
OnCalendar=monthly 
Persistent=true 

[Install] 
WantedBy=timers.target