Change the implementation of Admin#getServerNodes() as introducing a new API to get cluster information

[swuferhong]

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Description

Change the implementation of Admin#getServerNodes() as introducing a new API to get cluster information. In this way, we can realizing get ServerTag from this API instead of introducing a new API like showServerTags

Willingness to contribute

• I'm willing to submit a PR!

[gsralex]

Would you mind assigning this to me?

[swuferhong]

Hi, @gsralex. Could you briefly describe the API design and request/response design in the issue? Thanks a lot!

[LiebingYu]

Hi @swuferhong, I can take this.

My brief design:

1. Add ServerTag in ServerNode.
2. Add server_tag of MetadataResponse.
3. In the metadata rpc call, bring the serverTag to the return result both in CoordinatorServer and TabletServer.
4. Also we need to add the serverTag at the client side.

[swuferhong]

Hi, @LB-Yu. Maybe we can wait for @gsralex's reply. Additionally, if you're interested in the rebalance process, you might consider taking ownership of tasks such as #1398 #1399, but these pull requests (PRs) will depend on the task of #1397 and #1396.

About the API design. I agree with you to Add ServerTag in ServerNode. But, I think we can introduce a new request/response like DescribeClusterRequest/ DescribeClusterResponse. For each tabletServer, we can get the server info from ServerMetadataCache, and get serverTags from Zookeeper.

[swuferhong]

Hi, @LB-Yu. Maybe we can wait for @gsralex's reply. Additionally, if you're interested in the rebalance process, you might consider taking ownership of tasks such as #1398 #1399, but these two issue will depend on the task of #1397 and #1396.

About the API design. I agree with you to Add ServerTag in ServerNode. But, I think we can introduce a new request/response like DescribeClusterRequest/ DescribeClusterResponse. For each tabletServer, we can get the server info from ServerMetadataCache, and get serverTags from Zookeeper.

[swuferhong]

Hi, @LB-Yu. Maybe you can take this issue?

[LiebingYu]

Hi, @LB-Yu. Maybe you can take this issue?

Ok, I can take it.