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Preventing split-brain in HA Operators

Source: interviewadvanced

WHAT IT TESTS: leader election in controllers. OUTLINE: run active-passive replicas, only the leader reconciles, election uses a Lease object renewed under a TTL. RED FLAG: thinking all replicas reconcile in parallel or relying on optimistic locking alone.

WHAT IT TESTS: that HA Operators are active-passive, not active-active. ANSWER OUTLINE: multiple replicas exist for fast failover, but only the elected leader runs the reconcile loop; the rest stand by. Leadership is acquired by holding a coordination.k8s.io Lease, renewed within leaseDurationSeconds; if the leader stops renewing, a standby takes over. RED FLAG: claiming all pods reconcile concurrently, or that resourceVersion optimistic concurrency alone prevents duplicate work rather than just preventing conflicting writes.

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Preventing split-brain in HA Operators · Tezvyn