External `etcd` Support for Karmada Operator

[jabellard]

What type of PR is this?

/kind feature

What this PR does / why we need it: This is an implementation of this proposal for adding support to the Karmada operator for external etcd cluster connections.

Which issue(s) this PR fixes: Fixes #5242

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

The new `SecretRef` field added as part of the configuration for connecting to an external etcd cluster can be 
used to reference a secret that contains credentials for connecting to an external etcd cluster.

[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Once this PR has been reviewed and has the lgtm label, please assign poor12, rainbowmango for approval. For more information see the Kubernetes Code Review Process.

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• charts/OWNERS
• operator/OWNERS
• operator/pkg/apis/OWNERS

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[jabellard]

Hey @RainbowMango . This is still a work in progress, but I'd really appreciate some early feedback from you and the team to ensure we're well aligned on the way forward for the implementation of this feature.

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 124 lines in your changes missing coverage. Please review.

Project coverage is 34.80%. Comparing base (4c8bcd4) to head (b36b3d8). Report is 40 commits behind head on master.

Files with missing lines	Patch %	Lines
operator/pkg/controlplane/etcd/util.go	0.00%	45 Missing :warning:
operator/pkg/controlplane/apiserver/apiserver.go	0.00%	30 Missing :warning:
operator/pkg/tasks/deinit/component.go	0.00%	17 Missing :warning:
operator/pkg/controlplane/search/search.go	0.00%	14 Missing :warning:
operator/pkg/tasks/deinit/cert.go	0.00%	8 Missing :warning:
operator/pkg/init.go	0.00%	6 Missing :warning:
operator/pkg/deinit.go	0.00%	3 Missing :warning:
operator/pkg/tasks/init/component.go	0.00%	1 Missing :warning:

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5536      +/-   ##
==========================================
+ Coverage   34.14%   34.80%   +0.66%     
==========================================
  Files         643      646       +3     
  Lines       44524    44915     +391     
==========================================
+ Hits        15203    15634     +431     
+ Misses      28165    28074      -91     
- Partials     1156     1207      +51     

Flag	Coverage Δ
unittests	34.80% <0.00%> (+0.66%)	:arrow_up:

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[jabellard]

@RainbowMango , any thoughts?

[RainbowMango]

Hi @jabellard, As discussed at the community meeting, we will have an alpha release for feature #5478. And here it is: https://github.com/karmada-io/karmada/releases/tag/v1.12.0-alpha.1

[jabellard]

And here it is: https://github.com/karmada-io/karmada/releases/tag/v1.12.0-alpha.1

Thank you!

[RainbowMango]

@jabellard, please confirm whether we still need this PR.

[jabellard]

@jabellard, please confirm whether we still need this PR.

No longer needed. The other PRs covered the work initially introduced here.