Listener support/external access

[nightkr]

Description

Fixes #174, supersedes #175.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

Tasks before R4R

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1. Support external access
2. Support Kerberos
3. HDFS: Allow overriding datanode registration addresses docker-images#506
   5 of 5
   +0
4. Move listenerclass into role config? https://stackable-workspace.slack.com/archives/C02FZ581UCD/p1704714818413279
5. Add proper listener watch for discovery
6. Docs
7. Tests

Author

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1. Changes are OpenShift compatible
2. CRD changes approved
3. CRD documentation for all fields, following the style guide.
4. Helm chart can be installed and deployed operator works
5. Integration tests passed (for non trivial changes)
6. Changes need to be "offline" compatible

Reviewer

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1. Code contains useful comments
2. (Integration-)Test cases added
3. Documentation added or updated. Follows the style guide.
4. Changelog updated
5. Cargo.toml only contains references to git tags (not specific commits or branches)

Acceptance

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1. Feature Tracker has been updated
2. Proper release label has been added

[soenkeliebau]

Should we close #175 to avoid confusion?

[nightkr]

Sounds good yeah.

[nightkr]

Watching is blocked on stackabletech/listener-operator#138, but I wouldn't block on that since most expected changes here would be during startup/scale events (which would ping the operator anyway).

We'd still want to pull that out into an issue here and fix eventually, obviously.

[nightkr]

The current testing approach is blocked on kudobuilder/kuttl#322. Are we okay to punt on testing external access as long as the internal access tests still function?