SRE (Site Reliability Engineering)
Site Reliability Engineering
A practice that improves service reliability by using programming to automate the operation and maintenance of systems.
In Simple Terms
SRE is the practice of automating system management and monitoring with code, so that websites and apps keep running smoothly without trouble. Tasks that used to be done manually, like monitoring servers and recovering from failures, get handled automatically through custom-built programs instead. It's widely adopted to keep large-scale, high-traffic systems running reliably, such as major global social media platforms and video streaming services.
Behind the Name
SRE stands for Site, Reliability, and Engineering. The name reflects the idea of applying software development techniques to IT infrastructure operations, using code to solve problems and boost service reliability.
Take a Closer Look!
SRE refers to the concrete practices and mechanisms that use software development techniques to streamline and automate system operations, keeping websites and services running stably.
It puts the shared philosophy behind "DevOps" — breaking down the wall between development and operations — into practice within an organization, using specific numerical targets and strict rules.
What sets SRE apart most is its approach to managing reliability through numbers. Specifically, it measures service stability using an "SLI" (Service Level Indicator) and an "SLO" (Service Level Objective).
Working backward from these targets, it also defines an acceptable margin for failures called an "error budget." As long as budget remains, new features get released; once it's used up, releases are paused so the team can focus on stabilizing and recovering the system. This gives teams an objective rule for making that call.
SRE also sets a goal of keeping "toil" — repetitive manual work — under 50% of total working time. The remaining time, over 50%, is meant to go toward creative work that improves reliability, such as building automation tools.
In this way, SRE is an approach that structures operations around data and concrete rules, rather than relying on gut feeling.