Summary

The chapter started with the decomposition pattern, which is useful for breaking down a monolithic application into granularized, independent, and scalable modules. The FastAPI application that implemented these modules exhibited some principles included in the 12-Factor Application principles of a microservice, such as having independence, configuration files, logging systems, code bases, port binding, concurrency, and easy deployment.

Alongside decomposition, this chapter also showcased the mounting of different independent sub-applications onto the FastAPI platform. Only FastAPI can group independent microservices using mounts and bind them into one port with their corresponding context roots. From this feature, we created a pseudo-API Gateway pattern that serves as a façade to the independent sub-applications.

Despite the possible drawbacks, the chapter also highlighted domain modeling as an option for organizing components in a FastAPI microservice. The domain...