After installing a fresh Red Hat OpenShift cluster, go to Monitoring -> Alerting. There, you will find a Watchdog alert, which sends messages to let you know that Alertmanager is not only still running, but is also emitting other signals for alerts you might be interested in. You can hook into Watchdog alerts with an external monitoring system, which in turn can tell you that alerting in your OpenShift cluster is working.
“You need a check to check if your check checks out.”
How do you do this? Before we can configure Alertmanager for sending out Watchdog alerts, we need something on the receiving side, which is in our case Nagios. Follow me on this journey to get Alertmanager’s Watchdog alerting against Nagios with a passive check.
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