Looks like a very interesting piece of software. The declarative service file interface of systemd is a distinguishing feature no other supervisor supports (to my knowledge).

On a side note, I know that skarnet is working towards declarative service files as a possible interface in the next major versions of s6 and s6-rc:

https://skarnet.com/projects/service-manager.html#plan

>> Declarative service files. The model of unit files, where users can just write key=value lines instead of scripts, has been a resounding success for systemd — and it is also good end-user design (provided the parser correctly validates the files). And it can be done as a separate user interface layer, running on top of the more minimalistic engine.