fix: Prevent Pod 0 restart by utilizing mutating webhook

[sbernauer]

Description

Fixes #111

Many parts copied from https://github.com/stackabletech/commons-operator/tree/spike/sts-restarter-webhook

This bumps to operator-rs 0.101.1, but we don't have any objectOverrides to implement here.

Co-authored-by: Natalie Klestrup Röijezon nat@nullable.se

Definition of Done Checklist

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Author

• Changes are OpenShift compatible
• CRD changes approved
• CRD documentation for all fields, following the style guide.
• Helm chart can be installed and deployed operator works
• Integration tests passed (for non trivial changes)
• Changes need to be "offline" compatible
• Links to generated (nightly) docs added
• Release note snippet added

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• Code contains useful comments
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• (Integration-)Test cases added
• Documentation added or updated. Follows the style guide.
• Changelog updated
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Acceptance

• Feature Tracker has been updated
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Release notes

Fixed

• BREAKING: Prevent Pod 0 restart by utilizing a mutating webhook.
  The commons-operator now needs the RBAC permission to create and patch mutatingwebhookconfigurations, which the helm-chart automatically adds.
  The webhook can be disabled using --disable-restarter-mutating-webhook or by setting the DISABLE_RESTARTER_MUTATING_WEBHOOK env variable.

[dervoeti]

Nice, LGTM!

My tests worked as expected. One thing I found was that with airflow-operator the behavior is still the same (Pod 0 gets restarted), I believe this is because airflow-operator creates the ConfigMap after the StatefulSet: https://github.com/stackabletech/airflow-operator/blob/39d98ecd67a7bf29753551e01217faefafb53220/rust/operator-binary/src/airflow_controller.rs#L604-L628

So this could be a follow-up PR for airflow-operator. With superset-operator it worked fine.

[sbernauer]

I believe this is because airflow-operator creates the ConfigMap after the StatefulSet

Correct, we will change that :)

[sbernauer]

@dervoeti created stackabletech/superset-operator#694 and stackabletech/airflow-operator#734

[lfrancke]

Can you clarify the release notes for me? What is "pod 0"? Why does a mutating webhook help?
I'm not sure if you expand on this in the "parent issue" release notes.
The current sentence doesn't help me understand what's going on at least.
And I'd like to understand what happens when I disable the webhook.

Again: If you have or are planning to address this in the parent then that's fine.