prefix GVK labels in CustomResourceMonitoring

This will prefix the auto-generated GVK labels for CustomResources with
cr_ to make it a bit more clear that these labels got generated.

Signed-off-by: Mario Constanti <mario@constanti.de>

docs/customresourcestate-metrics.md

@@ -49,7 +49,7 @@ spec:
           - --resources=certificatesigningrequests,configmaps,cronjobs,daemonsets,deployments,endpoints,foos,horizontalpodautoscalers,ingresses,jobs,limitranges,mutatingwebhookconfigurations,namespaces,networkpolicies,nodes,persistentvolumeclaims,persistentvolumes,poddisruptionbudgets,pods,replicasets,replicationcontrollers,resourcequotas,secrets,services,statefulsets,storageclasses,validatingwebhookconfigurations,volumeattachments,verticalpodautoscalers
 ```
 
-NOTE: The `group`, `version`, and `kind` common labels are reserved, and will be overwritten by the values from the `groupVersionKind` field.
+NOTE: The `cr_group`, `cr_version`, and `cr_kind` common labels are reserved, and will be overwritten by the values from the `groupVersionKind` field.
 
 ### Examples
 

pkg/customresourcestate/registry_factory.go

@@ -32,15 +32,17 @@ import (
 	generator "k8s.io/kube-state-metrics/v2/pkg/metric_generator"
 )
 
+const gvkLabelPrefix string = "cr_"
+
 func compile(resource Resource) ([]compiledFamily, error) {
 	var families []compiledFamily
 	// Explicitly add GVK labels to all CR metrics.
 	if resource.CommonLabels == nil {
 		resource.CommonLabels = map[string]string{}
 	}
-	resource.CommonLabels["group"] = resource.GroupVersionKind.Group
-	resource.CommonLabels["version"] = resource.GroupVersionKind.Version
-	resource.CommonLabels["kind"] = resource.GroupVersionKind.Kind
+	resource.CommonLabels[gvkLabelPrefix+"group"] = resource.GroupVersionKind.Group
+	resource.CommonLabels[gvkLabelPrefix+"version"] = resource.GroupVersionKind.Version
+	resource.CommonLabels[gvkLabelPrefix+"kind"] = resource.GroupVersionKind.Kind
 	for _, f := range resource.Metrics {
 		family, err := compileFamily(f, resource)
 		if err != nil {