Opazljivost je sposobnost razumevanja notranjega stanja sistema na podlagi njegovih zunanjih rezultatov — preko logov, metrik in sledov (traces). Je ključna za obratovanje, odpravljanje napak in vzdrževanje sistemov (zlasti porazdeljenih), kjer ne morete upravljati tega, česar ne vidite.
Trije stebri opazljivosti
LOGS → timestamped records of events (what happened) → detailed, for debugging specific issues
METRICS → numerical measurements over time (CPU, latency, request rate, error rate) →
aggregate health/performance; dashboards; alerting
TRACES → follow a request's path through the system (across services) → understand flows,
find bottlenecks/failures in DISTRIBUTED systems (which service was slow?)
→ together: understand WHAT happened, the OVERALL state, and the PATH of requests.
