[Replication]Tracking the replication status of a cluster
We have this usecase where we want to bring down our live cluster,say cluster#1 (serving online traffic) for machine upgradation, and route the traffic during the upgrade to a backup cluster, say cluster#2
However, we want to drain the replication queue on cluster#1 before shutting it down completely. In other words we want the replication to be over on cluster#1 before we start the upgrade process.
I'm thinking about using the ReplicationZookeeper APIs to poll/watch the appropriate the RS znodes to do this(Haven't thought about the complete implementation details yet, just figuring out the feasibility part).
What do you guys think about it? Are there any caveats I should be aware of?