Implementing Service Level Objectives

Chapter 1. The Reliability Stack

Alex Hidalgo

We live in a world of services. There are vendors that will sell you Network as a Service or Infrastructure as a Service. You can pay for Monitoring as a Service or Database as a Service. And that doesn’t even touch upon the most widely used acronym, SaaS, which in and of itself can stand for Software, Security, Search, or Storage as a Service.

Furthermore, many organizations have turned to a microservice approach, one where you split functionality out into many small services that all talk to each other and depend on each other. Our systems are becoming more complex and distributed and deeper with every passing year.

It seems like everything is a service now, to the point that it can be difficult to define exactly what a service even is. If you run a retail website, you might have microservices that handle things like user authentication, payments systems, and keeping track of what a user has put in their shopping cart. But clearly, the entire retail website is itself also a service, albeit one that is composed of many smaller components.

We want to make sure our services are reliable, and to do this with—and within—complex systems, we need to start thinking about things in a different way than we may have in the past. You might be responsible for a globally distributed service with thousands of moving parts, or you might just be responsible for keeping a handful of VMs running. In either case, you almost certainly have human users ...