operator/pkg/certs: mitigate potential null pointer dereference in AltNames Mutators for both the APIServer and EtcdServer

[mohamedawnallah]

Description

In this commit, we fix the null pointer dereference issue that happens in altnames mutators for both Karmada APIServer and EtcdServer when accessing the Components field on AltNamesMutatorConfig struct.

Motivation and Context

In testing the Certificate Manager and Karmada Store (#5559), empty Components in AltNamesMutatorConfig struct triggered a null pointer dereference in both APIServer and EtcdServer AltNames mutators. This PR resolves that issue.

What type of PR is this?

/kind bug

Does this PR introduce a user-facing change?:

NONE

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[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 34.14%. Comparing base (671372a) to head (89794f1).
Report is 22 commits behind head on master.

Files with missing lines	Patch %	Lines
operator/pkg/certs/certs.go	0.00%	2 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5560      +/-   ##
==========================================
+ Coverage   33.71%   34.14%   +0.43%     
==========================================
  Files         643      643              
  Lines       44500    44524      +24     
==========================================
+ Hits        15001    15204     +203     
+ Misses      28357    28163     -194     
- Partials     1142     1157      +15     

Flag	Coverage Δ
unittests	34.14% <0.00%> (+0.43%)	⬆️

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[zhzhuang-zju]

@mohamedawnallah

karmada/operator/pkg/apis/operator/v1alpha1/defaults.go

Lines 78 to 94 in 4c8bcd4

	func setDefaultsKarmadaComponents(obj *Karmada) {
	if obj.Spec.Components == nil {
	obj.Spec.Components = &KarmadaComponents{}
	}
	setDefaultsEtcd(obj.Spec.Components)
	setDefaultsKarmadaAPIServer(obj.Spec.Components)
	setDefaultsKarmadaAggregatedAPIServer(obj.Spec.Components)
	setDefaultsKubeControllerManager(obj.Spec.Components)
	setDefaultsKarmadaControllerManager(obj.Spec.Components)
	setDefaultsKarmadaScheduler(obj.Spec.Components)
	setDefaultsKarmadaWebhook(obj.Spec.Components)
	setDefaultsKarmadaMetricsAdapter(obj.Spec.Components)
	setDefaultsKarmadaSearch(obj.Spec.Components)
	// set addon defaults
	setDefaultsKarmadaDescheduler(obj.Spec.Components)
	}

The karmada-operator initializes Components.Etcd and Components.KarmadaAPIServer by default, so in actual runtime, a null pointer exception will not occur.

/remove-kind bug
/kind cleanup

[mohamedawnallah]

@zhzhuang-zju The PR title might be a bit unclear. While it’s true that this issue wouldn't cause a null pointer dereference at runtime in Karmada as you said, testing etcdServerAltNamesMutator and apiServerAltNamesMutator as isolated units in the unit tests would lead to a null pointer dereference in case of empty Components in AltNamesMutatorConfig struct. What do you think?

[zhzhuang-zju]

How about operator/pkg/certs: mitigate potential null pointer dereference in AltNames Mutators for both the APIServer and EtcdServer