Chapter 4. Configuring external Alertmanager instances

Procedure

1. Edit the ConfigMap object.

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

      $ oc -n openshift-user-workload-monitoring edit configmap user-workload-monitoring-config

   2. Add a <component>/additionalAlertmanagerConfigs: section under data/config.yaml/.

   3. Add the configuration details for additional Alertmanagers in this section:

      apiVersion: v1
      kind: ConfigMap
      metadata:
        name: user-workload-monitoring-config
        namespace: openshift-user-workload-monitoring
      data:
        config.yaml: |
          <component>:
            additionalAlertmanagerConfigs:
            - <alertmanager_specification>

      For <component>, substitute one of two supported external Alertmanager components: prometheus or thanosRuler.

      For <alertmanager_specification>, substitute 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 using Thanos Ruler with a bearer token and client TLS authentication:

      apiVersion: v1
      kind: ConfigMap
      metadata:
        name: user-workload-monitoring-config
        namespace: openshift-user-workload-monitoring
      data:
        config.yaml: |
          thanosRuler:
            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

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