[Bug] `kyuubi.server.info.provider` set in `kyuubi-defaults.conf` is silently ignored

[Sunwoo-Shin]

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

Describe the bug

kyuubi.server.info.provider set in kyuubi-defaults.conf is silently ignored — KyuubiSessionImpl#getInfo always behaves as if the value were the default ENGINE; every TGetInfo call therefore waits for an engine to launch and is forwarded to it.

Root cause

SERVER_INFO_PROVIDER is marked .serverOnly. KyuubiSessionManager#openSession builds the per-session conf via getConf.getUserDefaults(user), which unsets every serverOnly entry before returning. As a result, sessionConf.get(SERVER_INFO_PROVIDER) in KyuubiSessionImpl#getInfo always returns the hard-coded default "ENGINE", regardless of kyuubi-defaults.conf.

It only appears to work in tests because they pass the value as a per-session overlay (withSessionConf(...)), which is re-applied after getUserDefaults.

Steps to reproduce

1. Set kyuubi.server.info.provider=SERVER in kyuubi-defaults.conf.
2. Connect via JDBC/beeline without overriding it per-session.
3. A GetInfo call still waits for an engine and the call is forwarded to it, instead of the server returning its own info directly.

Expected vs Actual

• Expected: server-level SERVER setting takes effect; getInfo returns Kyuubi server info immediately.
• Actual: server-level setting is dropped; getInfo always takes the ENGINE branch.

Suggested fix

Read SERVER_INFO_PROVIDER from the server-level conf, while still letting an explicit per-session override win:

val provider = sessionConf.getOption(SERVER_INFO_PROVIDER.key)
  .getOrElse(sessionManager.getConf.get(SERVER_INFO_PROVIDER))

Making the entry non-serverOnly would also fix it, but would change the semantics for all other usages and would let clients flip the mode, so the targeted fix is preferred.

Affects Version(s)

1.11.1

Kyuubi Server Log Output

N/A — no error is logged. The bug is a silent fallback to the default value.

Kyuubi Engine Log Output

N/A

Kyuubi Server Configurations

kyuubi.server.info.provider=SERVER

Kyuubi Engine Configurations

# N/A — engine-side config does not affect this bug.

Additional context

No response

Are you willing to submit PR?

• Yes. I would be willing to submit a PR with guidance from the Kyuubi community to fix.
• No. I cannot submit a PR at this time.