Description:

Using systemd to control synapse is mostly working, however we are currently unable to manage multiple workers in a 100% reliable fashion, as we cannot reliably tell when the master process has finished starting up compared to the worker processes.

It would be good to integrate with sd_notify such that if configured, synapse could pass READY=1 to systemd on a successful startup.

https://www.freedesktop.org/software/systemd/man/sd_notify.html

While working on this we could also provide the STATUS= to provide feedback on current state of synapse while starting [eg, if long-running background processes are going, such as DB re-indexing]