What are SLAs, SLOs, and SLIs?
⚡
Quick Answer
SLI is the measured indicator (e.g., success rate), SLO is the internal target on that indicator (e.g., 99.9%), and SLA is the external contract with customers (usually looser) that carries penalties if breached.
Detailed Answer
They nest: you measure an SLI, set an SLO above what the SLA promises to give yourself margin, and the SLA is the legal/commercial commitment. The difference between the SLO and 100% is the error budget that governs release risk. Getting the direction right (SLA <= SLO) is a common interview check.
💡
Interview Tip
State the ordering SLA is looser than SLO, and connect the SLO gap to the error budget.
slaslosli