Building Event-Driven Microservices, 2nd Edition

Chapter 15. Microservices Using Functions as a Service

Functions as a service (FaaS) are yet another way to build microservices. They’re a serverless solution for building, managing, and deploying applications via function building blocks, and provide significant value as a means of implementing relatively simple to modestly complex event-driven solutions.

A function is a piece of code that is executed when a specific triggering condition occurs. The function starts up, runs until completion, and then terminates. Scaling, state, and monitoring are typically provided by the FaaS framework, as is the requisitioning and releasing of compute resources. FaaS solutions can easily scale the number of function executions up and down depending on load, providing close tracking for highly variable loads.

It may be helpful to think of a FaaS solution as a basic consumer/producer implementation, but one that regularly and predictably stops after a predetermined amount of time. In many ways a FaaS solution is like a microservice that crashes every few minutes, but that stores its data in an external data store and can simply pick back up where it left off when it restarts.

Why Would I Use Functions as a Service?

FaaS solutions eliminate the overhead of creating and managing a microservice, provided you already have the FaaS framework set up and running. The biggest benefit of FaaS is the serverless aspect: you write the function code, specify when it should trigger, and deploy it. The FaaS ...