AlertmanagerClusterDown #

Meaning #

Half or more of the Alertmanager instances within the same cluster are down.

Impact #

You have an unstable cluster, if everything goes wrong you will lose the whole cluster.

Diagnosis #

Verify why pods are not running. You can get a big picture with events.

$ kubectl get events --field-selector involvedObject.kind=Pod | grep alertmanager

Mitigation #

There are no cheap options to mitigate this risk. Verifying any new changes in preprod before production environment should improve stability.