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Enable alerting high availability

You can enable alerting high availability support by updating the Grafana configuration file. If you run Grafana in a Kubernetes cluster, additional steps are required. Both options are described below. Please note that the deduplication is done for the notification, but the alert will still be evaluated on every Grafana instance. This means that events in alerting state history will be duplicated by the number of Grafana instances running.

Note

If using a mix of execute_alerts=false and execute_alerts=true on the HA nodes, since the alert state is not shared amongst the Grafana instances, the instances with execute_alerts=false will not show any alert status. This is because the HA settings (ha_peers, etc), only apply to the alert notification delivery (i.e. de-duplication of alert notifications, and silences, as mentioned above).

Enable alerting high availability in Grafana using Memberlist

Before you begin

Since gossiping of notifications and silences uses both TCP and UDP port 9094, ensure that each Grafana instance is able to accept incoming connections on these ports.

To enable high availability support:

  1. In your custom configuration file ($WORKING_DIR/conf/custom.ini), go to the [unified_alerting] section.
  2. Set [ha_peers] to the number of hosts for each Grafana instance in the cluster (using a format of host:port), for example, ha_peers=10.0.0.5:9094,10.0.0.6:9094,10.0.0.7:9094. You must have at least one (1) Grafana instance added to the ha_peers section.
  3. Set [ha_listen_address] to the instance IP address using a format of host:port (or the Pod’s IP in the case of using Kubernetes). By default, it is set to listen to all interfaces (0.0.0.0).
  4. Set [ha_peer_timeout] in the [unified_alerting] section of the custom.ini to specify the time to wait for an instance to send a notification via the Alertmanager. The default value is 15s, but it may increase if Grafana servers are located in different geographic regions or if the network latency between them is high.

Enable alerting high availability in Grafana using Redis

As an alternative to Memberlist, you can use Redis for high availability. This is useful if you want to have a central database for HA and cannot support the meshing of all Grafana servers.

  1. Make sure you have a redis server that supports pub/sub. If you use a proxy in front of your redis cluster, make sure the proxy supports pub/sub.
  2. In your custom configuration file ($WORKING_DIR/conf/custom.ini), go to the [unified_alerting] section.
  3. Set ha_redis_address to the redis server address Grafana should connect to.
  4. Optional: Set the username and password if authentication is enabled on the redis server using ha_redis_username and ha_redis_password.
  5. Optional: Set ha_redis_prefix to something unique if you plan to share the redis server with multiple Grafana instances.

The following metrics can be used for meta monitoring, exposed by Grafana’s /metrics endpoint:

MetricDescription
alertmanager_cluster_messages_received_totalTotal number of cluster messages received.
alertmanager_cluster_messages_received_size_totalTotal size of cluster messages received.
alertmanager_cluster_messages_sent_totalTotal number of cluster messages sent.
alertmanager_cluster_messages_sent_size_totalTotal number of cluster messages received.
alertmanager_cluster_messages_publish_failures_totalTotal number of messages that failed to be published.
alertmanager_cluster_membersNumber indicating current number of members in cluster.
alertmanager_peer_positionPosition the Alertmanager instance believes it’s in. The position determines a peer’s behavior in the cluster.
alertmanager_cluster_pings_secondsHistogram of latencies for ping messages.
alertmanager_cluster_pings_failures_totalTotal number of failed pings.

Enable alerting high availability using Kubernetes

If you are using Kubernetes, you can expose the pod IP through an environment variable via the container definition.

yaml
env:
  - name: POD_IP
    valueFrom:
      fieldRef:
        fieldPath: status.podIP
  1. Add the port 9094 to the Grafana deployment:
yaml
ports:
  - containerPort: 3000
    name: http-grafana
    protocol: TCP
  - containerPort: 9094
    name: grafana-alert
    protocol: TCP
  1. Add the environment variables to the Grafana deployment:
yaml
env:
  - name: POD_IP
    valueFrom:
      fieldRef:
        fieldPath: status.podIP
  1. Create a headless service that returns the pod IP instead of the service IP, which is what the ha_peers need:
yaml
apiVersion: v1
kind: Service
metadata:
  name: grafana-alerting
  namespace: grafana
  labels:
    app.kubernetes.io/name: grafana-alerting
    app.kubernetes.io/part-of: grafana
spec:
  type: ClusterIP
  clusterIP: 'None'
  ports:
    - port: 9094
  selector:
    app: grafana
  1. Make sure your grafana deployment has the label matching the selector, e.g. app:grafana:

  2. Add in the grafana.ini:

bash
[unified_alerting]
enabled = true
ha_listen_address = "${POD_IP}:9094"
ha_peers = "grafana-alerting.grafana:9094"
ha_advertise_address = "${POD_IP}:9094"
ha_peer_timeout = 15s