ORIGINAL SYSTEM DESIGN QUESTION
Scoped secret distribution
Deliver credentials to authorized services with rotation and audit history.
Original exercise · advanced. Editorial role relevance does not imply a company has asked this question.
Requirements and constraints
- 10,000 services; 1,000 credential lookups/second; rotate hourly.
- Expired/revoked credentials must not remain usable through uncontrolled caches.
- State assumptions and justify security, cost, operational ownership and data retention.
Pressure round
Rotation succeeds at the provider but consumers keep an old cached credential.
Build and explain the design
Requirements & scope
Who uses it? What must it do? What is explicitly out of scope? State latency, durability and privacy goals.
Self-review guidance
Define the actors, required operations and out-of-scope behavior. Explicit requirement: Expired/revoked credentials must not remain usable through uncontrolled caches.
Capacity estimates
State assumptions, peak requests/second, data volume and retention. Show your arithmetic and units.
Self-review guidance
Use this workload: 10,000 services; 1,000 credential lookups/second; rotate hourly. Convert rates and payload sizes into peak compute/storage assumptions; show units, headroom and what remains unmeasured.
APIs & data model
Describe endpoints/events, entity keys, indexes, authorization, and idempotency.
Self-review guidance
Define workload identity, secret versions and least-privilege grants.
Architecture & data flow
Describe components and request/event paths. Use plain text arrows to sketch your design; explain each responsibility.
Self-review guidance
Separate authorization, encrypted secret storage and rotation orchestration.
Failures & observability
What happens on overload, duplicate events, partial failures or lost dependencies? Discuss monitoring and recovery.
Self-review guidance
Pressure-test: Rotation succeeds at the provider but consumers keep an old cached credential. Describe bounded recovery, deduplication, observability and a user-visible failure state.
Tradeoffs & alternatives
Compare two plausible approaches. State the costs, consistency model and what would make you change the design.
Self-review guidance
Compare overlapping validity windows with rapid revocation and operational availability.
Design guidance describes assumptions and tradeoffs; no architecture has been simulated or benchmarked.
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