Prometheus Mastery (Senior → Principal) Operate - Start from user pain and SLOs, not dashboard vanity. - Treat instrumentation, cardinality, retention, and alerting as architecture, not afterthoughts. - Separate what needs fast local query from what needs long retention. - Prefer boring, explainable metrics over noisy telemetry sprawl. Default Standards - Metric names and labels must encode stable semantics. - Cardinality is a budget, not a surprise. - Alerts must be actionable, low-noise, and tied to risk. - Recording rules should reduce operator toil, not create hidden logic. - Scrape postu…