Implementing Service Level Objectives

Chapter 3. Developing Meaningful Service Level Indicators

Alex Hidalgo

The single most important aspect of adopting an SLO-based approach to reliability doesn’t even involve SLOs at all. SLIs are the most vital part of this entire process and system. There are several reasons for this, all of which boil down to the fact that human happiness is the ultimate end goal of using SLO-based approaches to running reliable services.¹ You can make lots of lives better if you take the time to develop meaningful SLIs.

SLIs are the foundation of the Reliability Stack. You can’t have reasonable SLO targets or useful error budgets if your SLIs aren’t meaningful. The entire stack becomes useless if it hasn’t been built upon something solid. You want to be able to have meaningful discussions and make meaningful decisions with the data an SLO-based approach can give you, and you won’t have good data to use if the measurements at the bottom of your stack aren’t good ones. Remember we defined a meaningful SLI as “a metric that tells you how your service is operating from the perspective of your users” in Chapter 1. It is this kind of meaningfulness that needs to travel up through the rest of your stack so you can make the most meaningful data-driven decisions with the data you produce.

Furthermore, your service isn’t reliable if your users don’t think it is. While many services only directly have users that are other services, there are still humans involved at every step along ...