This article details how to enable debug level logging on the Alertmanager instance in a Rancher v2.x managed Kubernetes cluster, which may assist when troubleshooting cluster or project alerting.



  • Within the Rancher UI navigate to the System Project of the relevant cluster and click on the Apps view.
  • Click ‘Upgrade’ on the cluster-alerting app.
  • In the Answers section click ‘Add Answer’ and add the variable alertmanager.logLevel with a value of debug.
  • Click upgrade to save the change and update the Alertmanager instance with the debug log level.
  • Navigate to the cattle-prometheus namespace within the System Project for the cluster, and view the logs of the alertmanager-cluster-alerting-0 Pod running for the alertmanager-cluster-alerting StatefulSet. You should see level=debug log messages, such as in the following example, confirming debug level logging has been successfully configured:
level=debug  ts=2019-07-09T15:03:37.511451301Z caller=dispatch.go:104  component=dispatcher msg="Received alert" alert=[433a194][active]
level=debug  ts=2019-07-09T15:03:38.511774835Z caller=dispatch.go:430  component=dispatcher  aggrGroup="{}/{group_id=\"c-5h85q:event-alert\"}/{rule_id=\"c-5h85q:event-alert_deployment-event-alert\"}:{event_message=\"Scaled  up replica set mynginx2-7994cd84ff to 1\",  resource_kind=\"Deployment\",  rule_id=\"c-5h85q:event-alert_deployment-event-alert\",  target_name=\"mynginx2\", target_namespace=\"default\"}" msg=flushing  alerts=[[433a194][active]]