Rollout flags are IMHO best implemented when they are pushed to the machines that need to read them by a technology like zookeeper. Pushed updates are then cach

Rollout flags are IMHO best implemented when they are pushed to the machines that need to read them by a technology like zookeeper. Pushed updates are then cached in memory by the machines receiving the updates and can be queried in the hotpath without having to worry about cache invalidation and the extra overhead of network calls.