valinor/kubernetes/apps/flux-system/add-ons/monitoring/prometheusrule.yaml

---
# yaml-language-server: $schema=https://ks.hsn.dev/monitoring.coreos.com/prometheusrule_v1.json
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: flux-rules
  namespace: flux-system
spec:
  groups:
    - name: flux.rules
      rules:
        - alert: FluxComponentAbsent
          annotations:
            summary: Flux component has disappeared from Prometheus target discovery.
          expr: |
            absent(up{job=~".*flux-system.*"} == 1)
          for: 15m
          labels:
            severity: critical
        - alert: FluxReconciliationFailure
          annotations:
            summary: >-
              {{ $labels.kind }} {{ $labels.namespace }}/{{ $labels.name }} reconciliation
              has been failing for more than 15 minutes.
          expr: |
            max(gotk_reconcile_condition{status="False",type="Ready"}) by (namespace, name, kind)
              +
            on(namespace, name, kind) (max(gotk_reconcile_condition{status="Deleted"})
              by (namespace, name, kind)) * 2 == 1
          for: 15m
          labels:
            severity: critical