setup service monitor for prometheus and alertanager

manifests/alertmanager/alertmanager-service.yaml

 apiVersion: v1
 kind: Service
 metadata:
+  labels:
+    alertmanager: main
   name: alertmanager-main
 spec:
   type: NodePort

manifests/prometheus/prometheus-k8s-service.yaml

 apiVersion: v1
 kind: Service
 metadata:
+  labels:
+    prometheus: k8s
   name: prometheus-k8s
 spec:
   type: NodePort

manifests/prometheus/prometheus-k8s-servicemonitors.yaml

@@ -44,3 +44,29 @@ spec:
     interval: 15s
   - port: http-metrics-skydns
     interval: 15s
+---
+apiVersion: monitoring.coreos.com/v1alpha1
+kind: ServiceMonitor
+metadata:
+  name: prometheus
+  labels:
+    prometheus: k8s
+spec:
+  endpoints:
+  - port: web
+  selector:
+    matchExpressions:
+    - {key: prometheus, operator: In, values: [k8s]}
+---
+apiVersion: monitoring.coreos.com/v1alpha1
+kind: ServiceMonitor
+metadata:
+  labels:
+    alertmanager: main
+  name: alertmanager
+spec:
+  endpoints:
+  - port: web
+  selector:
+    matchExpressions:
+    - {key: alertmanager, operator: In, values: [main]}
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