deprecate --master and --karmada-config flags for aggregrated-apiserver

[carlory]

Signed-off-by: carlory baofa.fan@daocloud.io

What type of PR is this?

/kind deprecation
/kind feature

What this PR does / why we need it:

informerfactory uses --kubeconfig to communicate with coreapiserver, we should reuse the same configuration.

func (o *CoreAPIOptions) ApplyTo(config *server.RecommendedConfig) error {
	if o == nil {
		return nil
	}

	// create shared informer for Kubernetes APIs
	var kubeconfig *rest.Config
	var err error
	if len(o.CoreAPIKubeconfigPath) > 0 {
		loadingRules := &clientcmd.ClientConfigLoadingRules{ExplicitPath: o.CoreAPIKubeconfigPath}
		loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, &clientcmd.ConfigOverrides{})
		kubeconfig, err = loader.ClientConfig()
		if err != nil {
			return fmt.Errorf("failed to load kubeconfig at %q: %v", o.CoreAPIKubeconfigPath, err)
		}
	} else {
		kubeconfig, err = rest.InClusterConfig()
		if err != nil {
			return err
		}
	}
	if feature.DefaultFeatureGate.Enabled(features.APIServerTracing) {
		kubeconfig.Wrap(traces.WrapperFor(config.TracerProvider))
	}
	clientgoExternalClient, err := clientgoclientset.NewForConfig(kubeconfig)
	if err != nil {
		return fmt.Errorf("failed to create Kubernetes clientset: %v", err)
	}
	config.ClientConfig = kubeconfig
	config.SharedInformerFactory = clientgoinformers.NewSharedInformerFactory(clientgoExternalClient, 10*time.Minute)

	return nil
}

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

deprecate --master and --karmada-config flags for karmada-aggregrated-apiserver

[XiShanYongYe-Chang]

Thanks, I use the redundant parameters.

LGTM

There are some errcheck need to be resolved.

[RainbowMango]

Please add a comment for when to remove it, such as:

// Remove it when we are in v1.2(+).

[RainbowMango]

Nice finding!

I found the description of --kubeconfig is weird:

--kubeconfig string                                       kubeconfig file pointing at the 'core' kubernetes server.

Can we update it?

diff --git a/cmd/aggregated-apiserver/app/options/options.go b/cmd/aggregated-apiserver/app/options/options.go
index b730778c..de9c9e0f 100644
--- a/cmd/aggregated-apiserver/app/options/options.go
+++ b/cmd/aggregated-apiserver/app/options/options.go
@@ -55,6 +55,7 @@ func NewOptions() *Options {
 // AddFlags adds flags to the specified FlagSet.
 func (o *Options) AddFlags(flags *pflag.FlagSet) {
        o.RecommendedOptions.AddFlags(flags)
+       flags.Lookup("kubeconfig").Usage = "Path to karmada control plane kubeconfig file."

        flags.StringVar(&o.karmadaConfig, "karmada-config", o.karmadaConfig, "Path to a karmada-apiserver KubeConfig.")

[RainbowMango]

The --kubeconfig modification could be done by #1342, this PR focus on deprecating thing.

[RainbowMango]

/approve

Leave LGTM to @XiShanYongYe-Chang

[karmada-bot]

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This pull-request has been approved by: RainbowMango

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[XiShanYongYe-Chang]

/lgtm