kube-prometheus: add dead man's switch

assets/alertmanager/alertmanager.yaml

@@ -5,8 +5,10 @@ route:
   group_wait: 30s
   group_interval: 5m
   repeat_interval: 12h
-  receiver: 'webhook'
+  receiver: 'null'
+  routes:
+  - match:
+      alertname: DeadMansSwitch
+    receiver: 'null'
 receivers:
-- name: 'webhook'
-  webhook_configs:
-  - url: 'http://alertmanagerwh:30500/'
+- name: 'null'

assets/prometheus/rules/general.rules

@@ -11,6 +11,18 @@ Alert TargetDown
     description = "A target of type {{ $labels.job }} is down."
   }
 
+### Dead man's switch ###
+
+ALERT DeadMansSwitch
+  IF vector(1)
+  LABELS {
+    severity = "none",
+  }
+  ANNOTATIONS {
+    summary = "Alerting DeadMansSwitch",
+    description = "This is a DeadMansSwitch meant to ensure that the entire Alerting pipeline is functional.",
+  }
+
 ### File descriptor alerts ###
 
 ALERT TooManyOpenFiles