Splitting the Monolith

In the previous chapter, we created a monolithic application to serve as an assistant; we did so rapidly, concentrating on adding features rather than long-term architecture. There is nothing wrong with that approach—after all if the application never needs to scale up then the engineering effort is wasted.

But let us assume that our service is very popular, and the number of requests it receives is growing. We now have to make sure it performs well under load, and also ensure that it is easy to maintain for a growing team of developers. How should we proceed from here? In this chapter, we will:

• Examine how to identify the best components to migrate to a new microservice based on code complexity and data we collect about usage
• Show techniques for preparing and performing that migration, as well as checking on its success