Merge pull request #25196 from luxas/auto_create_kube_system

Automatic merge from submit-queue

Automatically create the kube-system namespace

At the same time we ensure that the `default` namespace is present, it also creates `kube-system` if it doesn't exist.

`kube-system` will now exist from the beginning, and will be recreated every 10s if deleted, in the same manner as the `default` ns

This makes UX much better, no need for `kubectl`ing a `kube-system.yaml` file anymore for a function that is essential to Kubernetes (addons). For instance, this makes dashboard deployment much easier when there's no need to check for the `kube-system` ns first.

A follow up in the future may remove places where logic to manually create the kube-system namespace is present.

Also fixed a small bug where `CreateNamespaceIfNeeded` ignored the `ns` parameter and was hardcoded to `api.NamespaceDefault`.

@davidopp @lavalamp @thockin @mikedanese @bryk @cheld @fgrzadkowski @smarterclayton @wojtek-t @dlorenc @vishh @dchen1107 @bgrant0607 @roberthbailey

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plugin/pkg/admission/namespace/lifecycle/admission.go

@@ -36,7 +36,7 @@ const PluginName = "NamespaceLifecycle"
 
 func init() {
 	admission.RegisterPlugin(PluginName, func(client clientset.Interface, config io.Reader) (admission.Interface, error) {
-		return NewLifecycle(client, sets.NewString(api.NamespaceDefault)), nil
+		return NewLifecycle(client, sets.NewString(api.NamespaceDefault, api.NamespaceSystem)), nil
 	})
 }