We measure the connectivity from the shoot to the API Server. This is done via the blackbox exporter which is deployed in the shoot's kube-system namespace. Prometheus will scrape the blackbox exporter and then the exporter will try to access the API Server. Metrics are exposed if the connection was successful or not. This can be seen in the dashboard Kubernetes Control Plane Status dashboard under the API Server Connectivity panel. The shoot line represents the connectivity from the shoot.
In addition to the shoot connectivity, we also measure the seed connectivity. This means trying to reach the API Server from the seed via the external fully qualified domain name of the API server. The connectivity is also displayed in the above panel as the seed line. Both seed and shoot connectivity are shown below.
