[matthewowen]

A problem I've been thinking about recently is how you ensure that you have a DAG. Given a set of microservices that don't have a strict set of "tiering" rules, you don't necessarily know what services your dependency calls, and hence whether there is somewhere a dependency on you.

There are ways to minimize this, and certainly ways to instrument such that DAGs are detected, but I'm genuinely interested to know about how people are avoiding cyclic dependencies in their services. I think it's important, because if you're using containers, there's a good chance you're using (eg) readiness probes to determine if your containerized service can reach it's dependencies. If you have a cyclic dependency and something breaks, all of a sudden you can't bring up any containers in the cycle: A can't come up until B comes up, but B can't come up until A does.