Chapter 5. Configuring external Alertmanager instances

Procedure

1. Edit the cluster-monitoring-config config map in the openshift-monitoring project:

   $ oc -n openshift-monitoring edit configmap cluster-monitoring-config

2. Add an additionalAlertmanagerConfigs section with configuration details under data/config.yaml/prometheusK8s:

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: cluster-monitoring-config
     namespace: openshift-monitoring
   data:
     config.yaml: |
       prometheusK8s:
         additionalAlertmanagerConfigs:
         - <alertmanager_specification> 1

   1

   Substitute <alertmanager_specification> with authentication and other configuration details for additional Alertmanager instances. Currently supported authentication methods are bearer token (bearerToken) and client TLS (tlsConfig).

   The following sample config map configures an additional Alertmanager for Prometheus by using a bearer token with client TLS authentication:

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: cluster-monitoring-config
     namespace: openshift-monitoring
   data:
     config.yaml: |
       prometheusK8s:
         additionalAlertmanagerConfigs:
         - scheme: https
           pathPrefix: /
           timeout: "30s"
           apiVersion: v1
           bearerToken:
             name: alertmanager-bearer-token
             key: token
           tlsConfig:
             key:
               name: alertmanager-tls
               key: tls.key
             cert:
               name: alertmanager-tls
               key: tls.crt
             ca:
               name: alertmanager-tls
               key: tls.ca
           staticConfigs:
           - external-alertmanager1-remote.com
           - external-alertmanager1-remote2.com

3. Save the file to apply the changes. The pods affected by the new configuration are automatically redeployed.