Hey Colin, I think we should wait until after KIP-500's "bridge release" so there is a clean break from Zookeeper after 3.0. The bridge release by definition is an attempt to not break anything, so it theoretically doesn't warrant a major release. If that's not the case (i.e. if a single "bridge release" turns out to be impractical), we should consider forking 3.0 while maintaining a line of Zookeeper-dependent Kafka in 2.x. That way 3.x can evolve dramatically without breaking the 2.x line. In particular, anything related to removing Zookeeper could land in pre-3.0 while every other feature targets 2.6.
If you are proposing 2.6 should be the "bridge release", I think this is premature given Kafka's time-based release schedule. If the bridge features happen to be merged before 2.6's feature freeze, then sure -- let's make that the bridge release in retrospect. And if we get all the post-Zookeeper features merged before 2.7, I'm onboard with naming it "3.0" instead. That said, we should aim to remove legacy MirrorMaker before 3.0 as well. I'm happy to drive that additional breaking change. Maybe 2.6 can be the "bridge" for MM2 as well. Ryanne On Mon, May 4, 2020, 5:05 PM Colin McCabe <cmcc...@apache.org> wrote: > Hi all, > > We've had a few proposals recently for incompatible changes. One of them > is my KIP-604: Remove ZooKeeper Flags from the Administrative Tools. The > other is Boyang's KIP-590: Redirect ZK Mutation Protocols to the > Controller. I think it's time to start thinking about Kafka 3.0. > Specifically, I think we should move to 3.0 after the 2.6 release. > > From the perspective of KIP-500, in Kafka 3.x we'd like to make running in > a ZooKeeper-less mode possible (but not yet the default.) This is the > motivation behind KIP-590 and KIP-604, as well as some of the other KIPs > we've done recently. Since it will take some time to stabilize the new > ZooKeeper-free Kafka code, we will hide it behind an option initially. > (We'll have a KIP describing this all in detail soon.) > > What does everyone think about having Kafka 3.0 come up next after 2.6? > Are there any other things we should change in the 2.6 -> 3.0 transition? > > best, > Colin >
