What you will learn
- Define SLIs and SLOs
- Calculate error budgets
- Use budgets to balance velocity
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The basics, in plain English
How reliable should your service be? SLIs, SLOs, and error budgets are a way to answer that with numbers instead of guesses. You measure something users care about, set a target, and allow a small amount of failure as your budget. This keeps teams honest about reliability.
- SLI
- A Service Level Indicator: a measured number showing how well you are doing, like the percent of fast requests.
- SLO
- A Service Level Objective: the target you promise to hit, like 99.9 percent uptime.
- Error budget
- The small amount of failure you are allowed before breaking your promise.
- Uptime
- The percent of time your service is working and available.
- Reliability
- How dependably your service does what users expect.
- Why budgets
- They let you balance shipping new features against staying stable.
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Targets
An SLI measures something (availability), an SLO sets a target (99.9%), and the error budget is what you can afford to burn. It governs how fast you ship.
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