Health checks can have several purposes. They're used by the routing control plane to determine inclusion in the load balancer pool. This is already a kind of c

Health checks can have several purposes. They're used by the routing control plane to determine inclusion in the load balancer pool. This is already a kind of circuit breaker and is similar to what an application-level circuit breaker would poll. But they're also used by the scheduler to determine whether the instance needs to be restarted. You don't want your thing in a restart loop just because a dependency is down! In fact, if a very widely shared dependency went down, and everyone was checking it in their health check, the scheduler control plane could quickly have a backlog measured in days trying to move all those instances. Our environment now supports distinct answers to those two questions but most service authors don't know about it.