m/n/c/metrics: add kube-apiserver

This adds the Kubernetes API Server metrics to the list of exported
metrics.

Change-Id: Ie5827441362787a3bff03ec6cff1f07332b0ae34
Reviewed-on: https://review.monogon.dev/c/monogon/+/2335
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/node/core/metrics/exporters.go b/metropolis/node/core/metrics/exporters.go
index d39081c..270ec8b 100644
--- a/metropolis/node/core/metrics/exporters.go
+++ b/metropolis/node/core/metrics/exporters.go
@@ -55,6 +55,10 @@
 		Name: "kubernetes-controller-manager",
 		Port: node.MetricsKubeControllerManagerListenerPort,
 	},
+	{
+		Name: "kubernetes-apiserver",
+		Port: node.MetricsKubeAPIServerListenerPort,
+	},
 }
 
 func (e *Exporter) ServeHTTP(w http.ResponseWriter, r *http.Request) {