One of the best ways to fight complexity is to make your microservice autonomous. An autonomous service is a service that doesn't depend on other services in the system or third-party services. An autonomous service manages its own state and can be largely unaware of the rest of the system.
I like to think of autonomous microservices as similar to immutable functions. Autonomous services never change the state of other components in the system. The benefit of such services is that their complexity remains the same, regardless of how the rest of the system evolves and however they are being used by other services.
