Update kube-prometheus-stack values.yaml to clarify Loki datasource configuration and enhance observability documentation in CLUSTER-BUILD.md. Include deployment instructions for Loki and Fluent Bit, and mark tasks related to Grafana integration as completed.

clusters/noble/apps/grafana-loki-datasource/loki-datasource.yaml

@@ -0,0 +1,27 @@
+# Extra Grafana datasource — apply to **monitoring** (same namespace as kube-prometheus Grafana).
+# The Grafana sidecar watches ConfigMaps labeled **grafana_datasource: "1"** and loads YAML keys as files.
+# Does not require editing the kube-prometheus-stack Helm release.
+#
+#   kubectl apply -f clusters/noble/apps/grafana-loki-datasource/loki-datasource.yaml
+#
+# Remove with: kubectl delete -f clusters/noble/apps/grafana-loki-datasource/loki-datasource.yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: grafana-datasource-loki
+  namespace: monitoring
+  labels:
+    grafana_datasource: "1"
+data:
+  loki.yaml: |
+    apiVersion: 1
+    datasources:
+      - name: Loki
+        type: loki
+        uid: loki
+        access: proxy
+        url: http://loki-gateway.loki.svc.cluster.local:80
+        isDefault: false
+        editable: false
+        jsonData:
+          maxLines: 1000