Design leader election using Redis leases

Q: Design leader election using Redis leases

This question evaluates a candidate's understanding of distributed coordination and leader election using a central in-memory datastore, focusing on lease-based leadership, failover, and correctness under partitions and clock skew.

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Question

Leader/Follower via Redis (Lease-Based Leader Election)

You have N stateless service instances running the same job. At any time, exactly one instance should act as the leader (performing a singleton task), and the rest should be followers/standby.

You are allowed to use Redis as a coordination dependency (single primary Redis endpoint is fine for the interview). You may use any Redis features you want (e.g., SET NX PX, Lua scripts, Pub/Sub).

Requirements

Leader election: at most one leader at a time.
Failover: if the leader crashes or becomes unhealthy, a new leader should be elected within a bounded time.
Lease/heartbeat: leadership should be time-bounded and renewed.
Correctness concerns: discuss how you avoid or mitigate:
- split brain
- leader “sticking” after a crash
- clock skew assumptions
- network hiccups / GC pauses
Operational concerns: metrics/logging you’d add, and what happens if Redis is unavailable.

Deliverables

A clear algorithm/protocol description.
Key Redis data model (keys, TTLs, values).
Edge cases and how the system behaves.

Design leader election using Redis leases

Leader/Follower via Redis (Lease-Based Leader Election)

Requirements

Deliverables

Solution

Comments (0)

Design leader election using Redis leases

Overview

Leader/Follower via Redis (Lease-Based Leader Election)

Requirements

Deliverables

Solution

Comments (0)