[stable/prometheus-operator] Update KubeNodeUnreachable alert to fix #21371 (#22359)

* [stable/prometheus-operator] Update KubeNodeUnreachable alert to fix #21371

Signed-off-by: Sam Weston <weston.sam@gmail.com>

* [stable/prometheus-operator] Bump chart version

Signed-off-by: Sam Weston <weston.sam@gmail.com>

Co-authored-by: Reinhard Nägele <unguiculus@gmail.com>

stable/prometheus-operator/Chart.yaml

@@ -12,7 +12,7 @@ sources:
   - https://github.com/coreos/kube-prometheus
   - https://github.com/coreos/prometheus-operator
   - https://coreos.com/operators/prometheus
-version: 8.13.9
+version: 8.13.10
 appVersion: 0.38.1
 tillerVersion: ">=2.12.0"
 home: https://github.com/coreos/prometheus-operator

stable/prometheus-operator/templates/prometheus/rules-1.14/kubernetes-system-kubelet.yaml

@@ -36,8 +36,7 @@ spec:
       annotations:
         message: '{{`{{`}} $labels.node {{`}}`}} is unreachable and some workloads may be rescheduled.'
         runbook_url: {{ .Values.defaultRules.runbookUrl }}alert-name-kubenodeunreachable
-      expr: kube_node_spec_taint{job="kube-state-metrics",key="node.kubernetes.io/unreachable",effect="NoSchedule"} == 1
-      for: 2m
+      expr: (kube_node_spec_taint{job="kube-state-metrics",key="node.kubernetes.io/unreachable",effect="NoSchedule"} unless ignoring(key,value) kube_node_spec_taint{job="kube-state-metrics",key="ToBeDeletedByClusterAutoscaler"}) == 1
       labels:
         severity: warning
     - alert: KubeletTooManyPods
@@ -82,4 +81,4 @@ spec:
       labels:
         severity: critical
 {{- end }}
-{{- end }}
+{{- end }}