What is Site Reliability Engineering?
Length:
3 min
Published:
June 9, 2026
What is Site Reliability Engineering (SRE)?
Site Reliability Engineering (SRE) is a discipline that keeps software reliable by treating operations as a software problem. Instead of fixing servers by hand, SREs write code to automate the work, set measurable reliability targets, and use data to decide where to spend effort. The idea started at Google and is now common wherever uptime matters. The goal is not zero downtime, it is the right amount of reliability for the lowest sustainable cost.
In plain words
Think of an SRE as a pit crew engineer for a race team. They do not just patch the car when it breaks. They study every lap, set a target for how often a failure is acceptable, and build tools so the next pit stop is faster and safer. Their job is to keep the car running fast without burning out the team.
Core ideas
- SLIs, SLOs, and error budgets. An SLI measures something like uptime, an SLO is the target for it, and the error budget is how much failure you can afford before you slow down on new features.
- Toil reduction. Repetitive manual work gets automated, so engineers solve problems once instead of every week.
- Blameless postmortems. After an incident, the team studies what failed in the system, not who to blame.
Why it matters
- Reliability becomes measurable. You set clear targets and know when you are meeting them, instead of guessing.
- A healthy balance of speed and stability. The error budget gives a shared rule for when to ship fast and when to slow down.
- Less firefighting. Automation and good practices mean fewer 3 a.m. pages and more time for real work.
Common pitfalls
- Chasing 100% uptime. Perfect reliability costs far more than it returns, and the last fraction is rarely worth it.
- SRE as a rename for ops. Without automation and SLOs, it is the old job with a new title.
- SLOs nobody acts on. Targets only help if the team actually changes behaviour when the budget runs out.
Related articles:
- What is DevOps? - The wider culture of building and running software together.
- What is observability? - How SREs see what their systems are doing.
- What is incident management? - The process for handling outages when they happen.
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