Here is an excellent, in-depth discussion on creating scalable microservices.
In this article, we will look at microservices, not as a tool to scale the organization, development and release process (even though it’s one of the main reasons for adopting microservices), but from an architecture and design perspective, and put it in its true context: distributed systems. In particular, we will discuss how to leverage Events-first Domain Driven Design and Reactive principles to build scalable microservices, working our way through the evolution of a scalable microservices-based system.