feature(karmadactl): support split secret layout in init command

[tiansuo114]

What type of PR is this?
/kind feature

What this PR does / why we need it:
Part of #6670
Which issue(s) this PR fixes:

Fixes #6670

This commit introduces the capability for the karmadactl init command to deploy Karmada components using a split-style secret layout.

This change is part of a larger effort to refactor the certificate deployment mechanism within the karmadactl tool. It allows for a more granular and secure management of component certificates.

Special notes for your reviewer:

@chaosi-zju
@zhzhuang-zju
@XiShanYongYe-Chang

Does this PR introduce a user-facing change?:

`karmadactl`: Added the `--secret-layout` flag to the `init` command to support deploying with split certificate secrets.

[karmada-bot]

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[gemini-code-assist]

Summary of Changes

Hello @tiansuo114, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a significant enhancement to the karmadactl init command by enabling a 'split' secret layout for Karmada component certificates. This change provides more granular and secure management of TLS materials, moving away from a single aggregated secret to individual secrets for each component. This refactoring improves the overall security posture and aligns with best practices for certificate handling in Kubernetes environments.

Highlights

• New --secret-layout Flag: The karmadactl init command now supports a new --secret-layout flag, allowing users to choose between legacy (single aggregated secret) or split (per-component TLS secrets) for certificate management. The default behavior remains legacy.
• Granular Certificate Management: When the split secret layout is selected, Karmada components will now utilize individual TLS secrets for various services such as the API server, aggregated API server, etcd, kube-controller-manager, and webhook. This enhances security by isolating certificate materials per component.
• Dynamic Deployment Configuration: The deployment logic for Karmada components has been updated to dynamically adjust command-line arguments, volume mounts, and volume definitions based on the chosen secret layout, ensuring proper certificate loading for both legacy and split modes.
• New Certificate Constants and Generation Logic: A new pkg/cert/constants.go file has been introduced to centralize secret and key names for the split layout. Additionally, new Go functions have been added to generate and manage these individual secrets, including a fresh service account key pair for the API server and kube-controller-manager.

Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/installation-cli.yaml

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[Copilot]

Pull Request Overview

This PR adds support for a split secret layout in the karmadactl init command, allowing Karmada components to be deployed with per-component TLS secrets instead of a single aggregated secret. This provides more granular and secure certificate management.

Key changes:

• Added --secret-layout flag to control certificate secret organization (legacy vs split)
• Implemented split layout certificate generation creating separate TLS secrets per component
• Updated deployment manifests to mount appropriate secrets based on layout mode

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pkg/karmadactl/cmdinit/cmdinit.go	Added --secret-layout command line flag
pkg/karmadactl/cmdinit/config/types.go	Added SecretLayout field to KarmadaInitSpec configuration
pkg/karmadactl/cmdinit/kubernetes/deploy.go	Implemented split certificate secret creation logic
pkg/karmadactl/cmdinit/kubernetes/deployments.go	Updated deployments to support split secret mounting
pkg/karmadactl/cmdinit/kubernetes/statefulset.go	Modified etcd StatefulSet for split secret layout
pkg/cert/constants.go	New file defining TLS secret names and key constants
pkg/karmadactl/cmdinit/kubernetes/deployments_test.go	Added comprehensive tests for split layout functionality
pkg/karmadactl/cmdinit/kubernetes/statefulset_test.go	Added tests for etcd split secret configuration
hack/cli-testing-environment-split-secret.sh	Test script for split secret environment setup
.github/workflows/installation-cli.yaml	Added CI workflow for split secret testing

---

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[gemini-code-assist]

Code Review

This pull request introduces a --secret-layout flag to the karmadactl init command, allowing for a split-style secret layout. This is a valuable feature for improving security and manageability by creating per-component TLS secrets instead of a single aggregated one. The implementation is well-structured, with clear separation for the new 'split' layout and the 'legacy' layout, ensuring backward compatibility. The addition of pkg/cert/constants.go is a good practice for centralizing constants. The changes are also accompanied by thorough tests.

My main feedback revolves around significant code duplication in several functions that generate container commands for Karmada components. Refactoring these functions to eliminate duplication would greatly improve the code's maintainability. I've provided specific suggestions for these areas.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 66.04128% with 181 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.62%. Comparing base (712cf40) to head (6ffe7a3).
⚠️ Report is 12 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/karmadactl/cmdinit/kubernetes/deploy.go	45.96%	60 Missing and 27 partials ⚠️
pkg/karmadactl/cmdinit/kubernetes/deployments.go	70.34%	70 Missing and 16 partials ⚠️
pkg/karmadactl/cmdinit/kubernetes/statefulset.go	90.00%	7 Missing and 1 partial ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6788      +/-   ##
==========================================
- Coverage   45.77%   45.62%   -0.15%     
==========================================
  Files         689      689              
  Lines       57161    57360     +199     
==========================================
+ Hits        26164    26173       +9     
- Misses      29371    29517     +146     
- Partials     1626     1670      +44     

Flag	Coverage Δ
unittests	45.62% <66.04%> (-0.15%)	⬇️

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[tiansuo114]

The code passed CI/CD and works locally. I'm primarily interested in your feedback regarding scalability and design patterns. What is your opinion on the current architecture? @zhzhuang-zju