FEAT(grafana): add Thanos as default datasource

- Add Thanos Query as default Prometheus datasource
- Keep original Prometheus datasource as backup
- Thanos provides deduplicated metrics from HA Prometheus

REFACTOR(thanos): move all components to master node

- Add tolerations for control-plane:NoSchedule
- Add nodeSelector for control-plane node
- Affects: query, storegateway, compactor
- PVC will be recreated on master node (data in S3)

FIX(thanos): allow non-Bitnami images (quay.io/thanos)

FIX(thanos): correct nodeSelector value to 'true'

thanos/helm-values.yaml

@@ -7,6 +7,11 @@
 # - Store Gateway: reads historical data from MinIO
 # - Compactor: compacts and downsamples data in MinIO
 
+# Allow non-Bitnami images (quay.io/thanos/thanos)
+global:
+  security:
+    allowInsecureImages: true
+
 # Use quay.io image to avoid Docker Hub rate limits
 image:
   registry: quay.io
@@ -24,6 +29,14 @@ query:
   enabled: true
   replicaCount: 1
 
+  # Run on master node for stability
+  tolerations:
+    - key: node-role.kubernetes.io/control-plane
+      operator: Exists
+      effect: NoSchedule
+  nodeSelector:
+    node-role.kubernetes.io/control-plane: "true"
+
   # Deduplicate metrics from multiple Prometheus replicas
   dnsDiscovery:
     enabled: true
@@ -58,6 +71,14 @@ storegateway:
   enabled: true
   replicaCount: 1
 
+  # Run on master node for stability
+  tolerations:
+    - key: node-role.kubernetes.io/control-plane
+      operator: Exists
+      effect: NoSchedule
+  nodeSelector:
+    node-role.kubernetes.io/control-plane: "true"
+
   resources:
     requests:
       cpu: 15m
@@ -76,6 +97,14 @@ storegateway:
 compactor:
   enabled: true
 
+  # Run on master node for stability
+  tolerations:
+    - key: node-role.kubernetes.io/control-plane
+      operator: Exists
+      effect: NoSchedule
+  nodeSelector:
+    node-role.kubernetes.io/control-plane: "true"
+
   # Retention settings
   retentionResolutionRaw: 7d      # Keep raw data for 7 days
   retentionResolution5m: 30d      # Keep 5m downsampled for 30 days