Service level objectives (SLOs) specify a target level for the reliability of your service. Because SLOs are key to making data-driven decisions about reliability, they’re at the core of SRE practices. In many ways, this is the most important chapter in this book.
Once you’re equipped with a few guidelines, setting up initial SLOs and a process for refining them can be straightforward. Chapter 4 in our first book introduced the topic of SLOs and SLIs (service level indicators), and gave some advice on how to use them.
After discussing the motivation behind SLOs and error budgets, this chapter provides a step-by-step recipe to get you started thinking about SLOs, and also some advice about how to iterate from there. We’ll then cover how to use SLOs to make effective business decisions, and explore some advanced topics. Finally, we’ll give you some examples of SLOs for different types of services and some pointers on how to create more sophisticated SLOs in specific situations.1
Engineers are a scarce resource at even the largest organizations. Engineering time should be invested in the most important characteristics of the most important services. Striking the right balance between investing in functionality that will win new customers or retain current ones, versus investing in the reliability and scalability that will keep those customers happy, is difficult. ...