Update kube-prometheus-stack chart to v35

- Automate kube-prometheus-stack helm release upgrades for the v35.x range
- Remove deprecated Grafana settings
- Set Prometheus retention to 24h
- Label Flux dashboards and PodMonitors with `app.kubernetes.io/component: monitoring`
- Change the `podMonitorSelector` to match the label `app.kubernetes.io/component: monitoring`

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

manifests/monitoring/kube-prometheus-stack/namespace.yaml

@@ -2,3 +2,5 @@ apiVersion: v1
 kind: Namespace
 metadata:
   name: monitoring
+  labels:
+    app.kubernetes.io/component: monitoring

manifests/monitoring/kube-prometheus-stack/release.yaml

@@ -6,25 +6,28 @@ spec:
   interval: 5m
   chart:
     spec:
-      version: 34.7.0
+      version: "35.x"
       chart: kube-prometheus-stack
       sourceRef:
         kind: HelmRepository
         name: prometheus-community
-      interval: 1m
+      interval: 60m
   install:
     crds: Create
   upgrade:
     crds: CreateReplace
+  # https://github.com/prometheus-community/helm-charts/blob/main/charts/kube-prometheus-stack/values.yaml
   values:
     alertmanager:
       enabled: false
-    grafana:
-      sidecar:
-        dashboards:
-          searchNamespace: ALL
     prometheus:
       prometheusSpec:
+        retention: 24h
+        resources:
+          requests:
+            cpu: 200m
+            memory: 200Mi
+        podMonitorNamespaceSelector: {}
         podMonitorSelector:
           matchLabels:
-            app.kubernetes.io/part-of: flux
+            app.kubernetes.io/component: monitoring

manifests/monitoring/kube-prometheus-stack/repository.yaml

@@ -1,7 +1,7 @@
-apiVersion: source.toolkit.fluxcd.io/v1beta1
+apiVersion: source.toolkit.fluxcd.io/v1beta2
 kind: HelmRepository
 metadata:
   name: prometheus-community
 spec:
-  interval: 1m
+  interval: 120m
   url: https://prometheus-community.github.io/helm-charts

manifests/monitoring/monitoring-config/kustomization.yaml

@@ -6,8 +6,10 @@ resources:
 configMapGenerator:
   - name: flux-grafana-dashboards
     files:
-      - ../grafana/dashboards/control-plane.json
+      - dashboards/control-plane.json
-      - ../grafana/dashboards/cluster.json
+      - dashboards/cluster.json
     options:
       labels:
         grafana_dashboard: "1"
+        app.kubernetes.io/part-of: flux
+        app.kubernetes.io/component: monitoring

manifests/monitoring/monitoring-config/podmonitor.yaml

@@ -5,6 +5,7 @@ metadata:
   namespace: flux-system
   labels:
     app.kubernetes.io/part-of: flux
+    app.kubernetes.io/component: monitoring
 spec:
   namespaceSelector:
     matchNames: