feat: Replace endpoints with endpointslices as default resource

BREAKING CHANGE: endpoints are not a default resource anymore and
metrics need to be replaced with endpointslices' metrics.

https://kubernetes.io/blog/2025/04/23/kubernetes-v1-33-release/#deprecation-of-the-stable-endpoints-api.

Author: mrueg

docs/developer/cli-arguments.md

@@ -68,7 +68,7 @@ Flags:
       --pod string                                 Name of the pod that contains the kube-state-metrics container. When set, it is expected that --pod and --pod-namespace are both set. Most likely this should be passed via the downward API. This is used for auto-detecting sharding. If set, this has preference over statically configured sharding. This is experimental, it may be removed without notice.
       --pod-namespace string                       Name of the namespace of the pod specified by --pod. When set, it is expected that --pod and --pod-namespace are both set. Most likely this should be passed via the downward API. This is used for auto-detecting sharding. If set, this has preference over statically configured sharding. This is experimental, it may be removed without notice.
       --port int                                   Port to expose metrics on. (default 8080)
-      --resources string                           Comma-separated list of Resources to be enabled. Defaults to "certificatesigningrequests,configmaps,cronjobs,daemonsets,deployments,endpoints,horizontalpodautoscalers,ingresses,jobs,leases,limitranges,mutatingwebhookconfigurations,namespaces,networkpolicies,nodes,persistentvolumeclaims,persistentvolumes,poddisruptionbudgets,pods,replicasets,replicationcontrollers,resourcequotas,secrets,services,statefulsets,storageclasses,validatingwebhookconfigurations,volumeattachments"
+      --resources string                           Comma-separated list of resources to be enabled. Defaults to "certificatesigningrequests,configmaps,cronjobs,daemonsets,deployments,endpointslices,horizontalpodautoscalers,ingresses,jobs,leases,limitranges,mutatingwebhookconfigurations,namespaces,networkpolicies,nodes,persistentvolumeclaims,persistentvolumes,poddisruptionbudgets,pods,replicasets,replicationcontrollers,resourcequotas,secrets,services,statefulsets,storageclasses,validatingwebhookconfigurations,volumeattachments"
       --server-idle-timeout duration               The maximum amount of time to wait for the next request when keep-alives are enabled. Align with the idletimeout of your scrape clients. (default 5m0s)
       --server-read-header-timeout duration        The maximum duration for reading the header of requests. (default 5s)
       --server-read-timeout duration               The maximum duration for reading the entire request, including the body. Align with the scrape interval or timeout of scraping clients.  (default 1m0s)

jsonnet/kube-state-metrics/kube-state-metrics.libsonnet

@@ -358,7 +358,7 @@
       // extending the default container from above
       local c = ksm.deployment.spec.template.spec.containers[0] {
         args: [
-          '--resources=certificatesigningrequests,configmaps,cronjobs,daemonsets,deployments,endpoints,horizontalpodautoscalers,ingresses,jobs,leases,limitranges,mutatingwebhookconfigurations,namespaces,networkpolicies,nodes,persistentvolumeclaims,persistentvolumes,poddisruptionbudgets,replicasets,replicationcontrollers,resourcequotas,secrets,services,statefulsets,storageclasses,validatingwebhookconfigurations,volumeattachments',
+          '--resources=certificatesigningrequests,configmaps,cronjobs,daemonsets,deployments,endpointslices,horizontalpodautoscalers,ingresses,jobs,leases,limitranges,mutatingwebhookconfigurations,namespaces,networkpolicies,nodes,persistentvolumeclaims,persistentvolumes,poddisruptionbudgets,replicasets,replicationcontrollers,resourcequotas,secrets,services,statefulsets,storageclasses,validatingwebhookconfigurations,volumeattachments',
         ],
       };
       std.mergePatch(

pkg/options/options.go

@@ -167,7 +167,7 @@ func (o *Options) AddFlags(cmd *cobra.Command) {
 	o.cmd.Flags().Var(&o.MetricOptInList, "metric-opt-in-list", "Comma-separated list of metrics which are opt-in and not enabled by default. This is in addition to the metric allow- and denylists")
 	o.cmd.Flags().Var(&o.Namespaces, "namespaces", fmt.Sprintf("Comma-separated list of namespaces to be enabled. Defaults to %q", &DefaultNamespaces))
 	o.cmd.Flags().Var(&o.NamespacesDenylist, "namespaces-denylist", "Comma-separated list of namespaces not to be enabled. If namespaces and namespaces-denylist are both set, only namespaces that are excluded in namespaces-denylist will be used.")
-	o.cmd.Flags().Var(&o.Resources, "resources", fmt.Sprintf("Comma-separated list of Resources to be enabled. Defaults to %q", &DefaultResources))
+	o.cmd.Flags().Var(&o.Resources, "resources", fmt.Sprintf("Comma-separated list of resources to be enabled. Defaults to %q", &DefaultResources))
 
 	o.cmd.Flags().DurationVar(&o.ServerReadTimeout, "server-read-timeout", defaultServerReadTimeout, "The maximum duration for reading the entire request, including the body. Align with the scrape interval or timeout of scraping clients. ")
 	o.cmd.Flags().DurationVar(&o.ServerWriteTimeout, "server-write-timeout", defaultServerWriteTimeout, "The maximum duration before timing out writes of the response. Align with the scrape interval or timeout of scraping clients..")

pkg/options/resource.go

@@ -31,7 +31,7 @@ var (
 		"cronjobs":                        struct{}{},
 		"daemonsets":                      struct{}{},
 		"deployments":                     struct{}{},
-		"endpoints":                       struct{}{},
+		"endpointslices":                  struct{}{},
 		"horizontalpodautoscalers":        struct{}{},
 		"ingresses":                       struct{}{},
 		"jobs":                            struct{}{},