SLO vs. SLA vs. SLI: Understanding the basics of SRE

Service Reliability Engineering (SRE) is a discipline that combines software engineering, operations, and systems reliability principles to ensure services are highly available, reliable, and resilient. It involves designing incident management software stacks, leveraging automated systems to monitor service health, performing operational tasks, capacity planning, and automating response actions. SRE teams work on building internal systems and processes to serve both external customers and internal stakeholders such as software development or engineering teams. Service Level Objectives (SLOs) measure overall service performance by defining the required availability, latency, and errors of a system. They are set to achieve customer satisfaction while balancing cost-efficiency goals. Service Level Agreements (SLAs), on the other hand, are contractual agreements between a provider and a client regarding the service performance of an SRE team. SLAs outline support provided, incident response times, turnaround for fixes/changes made by engineers, and potential incentives or penalties for meeting or not meeting these commitments. Service Level Indicators (SLIs) are metrics or actual measurements used to track, monitor, and report on an SRE team's performance. They help provide visibility into overall system health so that potential issues can be quickly identified and addressed before they become bigger problems. Together, SLOs, SLAs, and SLIs form the foundation of a successful SRE practice, ensuring service reliability while balancing cost-efficiency goals.