DevOps for Site Reliability Engineering: 7.1 Introduction: What SRE Actually Is 66 7.1.1 Origin 66 7.1.2 SRE, DevOps, and Platform Engineering 67 7.2 Service Levels 67 7.2.1 The Three Terms 67 7.2.2 Writing a Good SLI 68 7.2.3 The Golden Signals 68 7.2.4 Choosing the Target 68 7.3 Error Budgets

Learning Objectives

By the end of this chapter, you will be able to:

1. Explain what SRE is, where it came from, and how it differs from operations, DevOps, and platform engineering.
2. Distinguish SLIs, SLOs, and SLAs, and write a well-formed SLI specification for a real service.
3. Set a reliability target justified by user expectation and dependency reality rather than by round numbers.
4. Operate an error budget, including the policy that determines what happens when it is exhausted.
5. Design burn-rate alerting that pages on user impact rather than on component symptoms.
6. Build an observability practice covering metrics, logs, and traces, and manage its cardinality and cost.
7. Run incidents with defined roles and conduct post-incident reviews that produce learning rather than blame.
8. Apply capacity, performance, and resilience engineering: percentiles, tail latency, retry behavior, load shedding, and chaos experiments.
9. Assess where AI and agentic automation can safely hold authority in reliability work, and where automation itself becomes a hazard.
10. Recognize the anti-patterns that cause most enterprise SRE programmes to fail.