After the migration to the new server, my old SysV init script for restarting the queue daemons needed to be updated to systemd.
I have been very skeptical, if not hostile, towards the very concept of systemd. However, creating a GNUsocial service file was very simple, and works remarkably well.
Here is the service file:
After=network.target mysql.service nginx.service
# Note: we use nginx, so your server may vary
# PIDfile directory should match the value in your config.php!
Tags: linux server gnusocial