Code Room
System designHardsd-g478
Subject Rbac abacLevel Senior–Staff~45 minCommon in Distributed systems interviewsIndustries Technology, Software development

Question

Design the change-management / safe-rollout pipeline for an authorization policy system used company-wide, where a single bad policy edit can either lock everyone out (over-restrictive) or open a hole (over-permissive), and policies change dozens of times a day across many teams. Beyond the runtime decision engine, design how a policy change is validated, dry-run, and rolled out safely. Discuss policy versioning, shadow/dual evaluation against real traffic, automated impact analysis ('this change would newly DENY 4,200 requests/day'), staged rollout, and instant rollback — all while the engine answers millions of decisions/sec.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Narrate your design
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Run or narrate your approach, then ask the coach.