[Umbrella] Support service discovery through etcd

[hddong]

Code of Conduct

• [X] I agree to follow this project's Code of Conduct

Search before asking

• [X] I have searched in the issues and found no similar issues.

Describe the proposal

On k8s, if we not had a zk yeet, we can use the existing etcd for service discovery.

Task list

• #1404
• #1505
• #2631
• #2644
• #3104
• #3141

Are you willing to submit PR?

• [X] Yes I am willing to submit a PR!

[pan3793]

Would you please describe your plan in more detail?

[hddong]

Sure.

The modules:

kyuubi-ha
  - kyuubi-ha-common
  - kyuubi-ha-zookeeper
  - kyuubi-ha-etcd

Implementation

There are mainly two classes, ServiceDiscovery and ZooKeeperClientProvider, for other modules to use.

1. ServiceDiscovery

• use a new class AbstractInstanceClient instead of zkClient

• Move static functions in ServiceDiscovery to DiscoveryClient DiscoveryClient contains discovery api( E.g createServiceNodeAndGetPath, getServiceNodesInfo) and client api (E.g getChildren, delete).

2. ZooKeeperClientProvider Abstract as DiscoveryClientProvider

Usages

In other modules, original:

withZkClient(conf) { framework =>
      createServiceNodeAndGetPath(conf, framework, uniqueNamespace, "localhost:10000")
      framework.delete().forPath(nodePath)
}

we can change to:

withDiscoveryClient(conf) { framework =>
      framework.createServiceNodeAndGetPath(conf, uniqueNamespace, "localhost:10000")
      framework.delete(nodePath)
}

[hddong]

cc @pan3793 @yaooqinn @ulysses-you

[yaooqinn]

look good to me, can these be put in the same module？

[hddong]

look good to me, can these be put in the same module？

Sure.

[charlesy6]

hi, it seems we still need zookeeper cluster, we expose kyuubi server to zookeeper, hive client can connect to server by zookeeper. how the hive client use etcd?

[hddong]

hi, it seems we still need zookeeper cluster, we expose ...how the hive client use etcd?

Yes, it does not support server discovery by default. Maybe we have two solutions: zetcd(It hasn't been updated for a while), or we can provide a client or jar support etcd. And, on kubernetes, may be one server is acceptable.