I’m a big fan of following the Single Responsibility Principle when creating Lambda functions in my serverless applications. The idea of each function doing “one thing well” allows you to easily separate discrete pieces of business logic into reusable components. In addition, the Lambda concurrency model, along with the ability to add fine-grained IAM permissions per function, gives you a tremendous amount of control over the security, scalability, and cost of each part of your application.
However, there are several drawbacks with this approach that often attract criticism. These include things like increased complexity, higher likelihood of cold starts, separation of log files, and the inability to easily compose functions. I think there is merit to these criticisms, but I have personally found the benefits to far outweigh any of the negatives. A little bit of googling should help you find ways to mitigate many of these concerns, but I want to focus on the one that seems to trip most people up: function composition.
Thinking about microservices, especially their communication patterns, can be a bit of a mind-bending experience for developers. The idea of splitting an application into several (if not hundreds of) independent services, can leave even the most experienced developer scratching their head and questioning their choices. Add serverless event-driven architecture into the mix, eliminating the idea of state between invocations, and introducing a new per function concurrency model that supports near limitless scaling, it’s not surprising that many developers find this confusing. 😕 But it doesn’t have to be. 😀
In this post, we’ll outline a few principles of microservices and then discuss how we might implement them using serverless. If you are familiar with microservices and how they communicate, this post should highlight how these patterns are adapted to fit a serverless model. If you’re new to microservices, hopefully you’ll get enough of the basics to start you on your serverless microservices journey. We’ll also touch on the idea of orchestration versus choreography and when one might be a better choice than the other with serverless architectures. I hope you’ll walk away from this realizing both the power of the serverless microservices approach and that the basic fundamentals are actually quite simple. 👊