Created attachment 422404 [details, diff]
Allow systemd unit files to declare dependency on postgresql.service (some currently in tree e.g. net-analyzer/zabbix).
If a user wants dependencies on specific versions of postgresql with systemd they can do so with drop-ins in /etc/systemd/system - they would likely be doing this anyway to run multiple versions of PostgreSQL itself e.g. to specify a different PGPORT.
I actually worked on removing this very thing from the initscripts/eselect as it is actually detrimental as it hides which slot will be brought up.
If systemd is incapable of expressing a generic provide and/or dependency, then systemd needs to be fixed.
However, thank you for your effort. If the systemd service files can be improved in some way, without hiding which slot will be used, I'll be happy to consider those as well.