Possibility to create nodes with TTL

[dlanza1]

Hi,

Current versions of Zookeeper allow to specify a TTL for node removal. What about making this library compatible with that?

Thanks in advance,
Daniel

[jeffwidman]

Pull requests are welcome. Currently I (and AFAIK the other maintainers) don't have much bandwidth to add new features, but I do try to review PRs.

[nakulpathak3]

What work would this entail? If someone could describe this better and if it's not a crazy amount of work, I could pick it up.

[nakulpathak3]

From quick first review, it seems like we'd be adding support for https://zookeeper.apache.org/doc/r3.5.4-beta/zookeeperProgrammers.html#TTL+Nodes.

The code would go somewhere here https://github.com/python-zk/kazoo/blob/master/kazoo/client.py#L812-L963 (along with changes to test). I can't find the API call to make in the API/Java Client https://zookeeper.apache.org/doc/r3.4.6/api/org/apache/zookeeper/ZooKeeper.html#create(java.lang.String,%20byte[],%20java.util.List,%20org.apache.zookeeper.CreateMode). Any tips on what the API call would look like will be helpful!

Other info:
Seems like it's only supported for PERSISTENT and PERSISTENT_SEQUENTIAL type nodes. And that it's not enabled by default in zookeeper right now (mentioned in the TTL Node description link above)

[StephenSorriaux]

@nakulpathak3 I think you are right, a new parameter ttl could be added to the create() and create_async() methods with, I guess, default to None.

I think you didn't find the ttl parameter in the Java client because this feature was added for the 3.5.3 version and you were looking at the 3.4.6 version. I found the method here: https://zookeeper.apache.org/doc/r3.5.4-beta/api/org/apache/zookeeper/ZooKeeper.html#create-java.lang.String-byte:A-java.util.List-org.apache.zookeeper.CreateMode-org.apache.zookeeper.data.Stat-long-

As far as I can see in the code (https://github.com/apache/zookeeper/blob/release-3.5.4/src/java/main/org/apache/zookeeper/ZooKeeper.java#L1634), it requires the CreateTTL request that we currently don't have in the client. You will need to add it the kazoo.protocol.serialization module with type=21 (https://github.com/apache/zookeeper/blob/cb9f303bda9137d1aebe8eff3eab85c8a59f3cdd/zookeeper-server/src/main/java/org/apache/zookeeper/ZooDefs.java#L75 & https://github.com/apache/zookeeper/blob/release-3.5.4/src/zookeeper.jute#L130).

Since you need a specific zookeeper configuration for the test, I suggest you to use what I developed when I added the SASL support (https://github.com/python-zk/kazoo/blob/master/kazoo/testing/harness.py#L42-L51)

[nakulpathak3]

I won't have time to tackle this for the next few weeks unfortunately so if someone else sees this and wants to until then, go ahead. If not, I'll come back around mid February.

[shoundhariya]

I will take this up.