Adjust the Prometheus service discovery for the etcd pods (gardener#8371

)

The labels on the etcd service changed with
gardener/etcd-druid#559 that was introduced in
gardener#8299.

The `app` and `role` labels are no longer present on the service, but they are
still available on the pods.

So by using the pod's labels for the service discovery, we can restore the
previous behavior.

https://prometheus.io/docs/prometheus/latest/configuration/configuration/#endpoints

Co-authored-by: Jeremy Rickards <jeremy.rickards@sap.com>

pkg/component/etcd/monitoring.go

@@ -302,12 +302,12 @@ kubernetes_sd_configs:
     names: [{{ .namespace }}]
 relabel_configs:
 - source_labels:
-  - __meta_kubernetes_service_label_` + v1beta1constants.LabelApp + `
-  - __meta_kubernetes_service_label_` + v1beta1constants.LabelRole + `
+  - __meta_kubernetes_pod_label_` + v1beta1constants.LabelApp + `
+  - __meta_kubernetes_pod_label_` + v1beta1constants.LabelRole + `
   - __meta_kubernetes_endpoint_port_name
   action: keep
   regex: ` + LabelAppValue + `;{{ .role }};` + portNameClient + `
-- source_labels: [ __meta_kubernetes_service_label_` + v1beta1constants.LabelRole + ` ]
+- source_labels: [ __meta_kubernetes_pod_label_` + v1beta1constants.LabelRole + ` ]
   target_label: role
 - source_labels: [ __meta_kubernetes_pod_name ]
   target_label: pod
@@ -332,12 +332,12 @@ kubernetes_sd_configs:
     names: [{{ .namespace }}]
 relabel_configs:
 - source_labels:
-  - __meta_kubernetes_service_label_` + v1beta1constants.LabelApp + `
-  - __meta_kubernetes_service_label_` + v1beta1constants.LabelRole + `
+  - __meta_kubernetes_pod_label_` + v1beta1constants.LabelApp + `
+  - __meta_kubernetes_pod_label_` + v1beta1constants.LabelRole + `
   - __meta_kubernetes_endpoint_port_name
   action: keep
   regex: ` + LabelAppValue + `;{{ .role }};` + portNameBackupRestore + `
-- source_labels: [ __meta_kubernetes_service_label_role ]
+- source_labels: [ __meta_kubernetes_pod_label_role ]
   target_label: role
 - source_labels: [ __meta_kubernetes_pod_name ]
   target_label: pod

pkg/component/etcd/monitoring_test.go

@@ -175,12 +175,12 @@ kubernetes_sd_configs:
     names: [` + testNamespace + `]
 relabel_configs:
 - source_labels:
-  - __meta_kubernetes_service_label_app
-  - __meta_kubernetes_service_label_role
+  - __meta_kubernetes_pod_label_app
+  - __meta_kubernetes_pod_label_role
   - __meta_kubernetes_endpoint_port_name
   action: keep
   regex: etcd-statefulset;` + testRole + `;client
-- source_labels: [ __meta_kubernetes_service_label_role ]
+- source_labels: [ __meta_kubernetes_pod_label_role ]
   target_label: role
 - source_labels: [ __meta_kubernetes_pod_name ]
   target_label: pod
@@ -204,12 +204,12 @@ kubernetes_sd_configs:
     names: [` + testNamespace + `]
 relabel_configs:
 - source_labels:
-  - __meta_kubernetes_service_label_app
-  - __meta_kubernetes_service_label_role
+  - __meta_kubernetes_pod_label_app
+  - __meta_kubernetes_pod_label_role
   - __meta_kubernetes_endpoint_port_name
   action: keep
   regex: etcd-statefulset;` + testRole + `;backuprestore
-- source_labels: [ __meta_kubernetes_service_label_role ]
+- source_labels: [ __meta_kubernetes_pod_label_role ]
   target_label: role
 - source_labels: [ __meta_kubernetes_pod_name ]
   target_label: pod