upgrade pulsar 2.7.x to 2.10.x: curator and zookeeper compatibility problem

[Maslino]

Pulsar 2.7.x uses curator 4 and zookeeper 3.5.x
From Pulsar 2.8.x onwards, pulsar uses curator 5 and zookeeper 3.6.x

I want to upgrade pulsar 2.7.x to 2.10.x, but face the problem of compatibility between curator library and zookeeper server.

Following the upgrade guidelines from pulsar docs, the upgrade sequence is firstly zookeeper then bookkeeper and then broker. And zookeeper upgrade is optional.

If I choose to not to upgrade zookeeper: are bookkeeper and broker of pulsar 2.10.x compatible with zookeeper 3.5.x of pulsar 2.7.x?
If I choose to upgrade zookeeper: is bookkeeper of pulsar 2.7.x compatible with zookeeper 3.6.x of pulsar 3.10.x?

As far as I know, pulsar 2.10.x is not compatible with zookeeper 3.5.x

Is pulsar 2.7.x compatible with zookeeper 3.6.x ?

[hezhangjian]

I think it will works

[tisonkun]

I don't remember that we use any new features of ZK/Curator on the Pulsar side, so such ZK/Curator version shift should all work.

cc @eolivelli @merlimat

[tisonkun]

BTW, perhaps a compatible matrix helps?

[Maslino]

issue #14675 shows that pulsar 2.10.x is not compatible with ZK 3.5.x

When I upgrade pulsar 2.7.4 to 2.10.3 without ZK upgrade, bookie seems OK but broker throws the same exception (UnimplementedException: KeeperErrorCode = Unimplemented for /) as described in the above issue failing to start.

[tisonkun]

@Maslino I think it's because the zk client in broker classpath is >= 3.6.3. You may try to replace the zookeeper JARs under $PULSAR_HOME/lib with 3.5.x version and see what happens.

Curator conditionally uses new features based on what version of ZK in the classpath.

[Maslino]

I am using the official pulsar-all docker image.

[tisonkun]

Well. Then it can be a problem 🤣

[hezhangjian]

@Maslino would you mind rebuild a image to replace zookeeper library inside lib directory?