In the past I've used a single repo with all the code which gets pushed everywhere, and each service only runs it's portion of the code. No guess work involved,

In the past I've used a single repo with all the code which gets pushed everywhere, and each service only runs it's portion of the code. No guess work involved, but this may not work for a lot of setups of course. That and your graceful restart logic has to be slightly more involved.