Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.
Configure high availability
Grafana Alerting uses the Prometheus model of separating the evaluation of alert rules from the delivering of notifications. In this model, the evaluation of alert rules is done in the alert generator and the delivering of notifications is done in the alert receiver. In Grafana Alerting, the alert generator is the Scheduler and the receiver is the Alertmanager.
When running multiple instances of Grafana, all alert rules are evaluated on all instances. You can think of the evaluation of alert rules as being duplicated by the number of running Grafana instances. This is how Grafana Alerting makes sure that as long as at least one Grafana instance is working, alert rules will still be evaluated and notifications for alerts will still be sent.
You can find this duplication in state history and it is a good way to confirm if you are using high availability.
While the alert generator evaluates all alert rules on all instances, the alert receiver makes a best-effort attempt to avoid sending duplicate notifications. Alertmanager chooses availability over consistency, which may result in occasional duplicated or out-of-order notifications. It takes the opinion that duplicate or out-of-order notifications are better than no notifications.
The Alertmanager uses a gossip protocol to share information about notifications between Grafana instances. It also gossips silences, which means a silence created on one Grafana instance is replicated to all other Grafana instances. Both notifications and silences are persisted to the database periodically, and during graceful shut down.
Note
If using a mix ofexecute_alerts=false
andexecute_alerts=true
on the HA nodes, since the alert state is not shared amongst the Grafana instances, the instances withexecute_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 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:
- In your custom configuration file ($WORKING_DIR/conf/custom.ini), go to the
[unified_alerting]
section. - Set
[ha_peers]
to the number of hosts for each Grafana instance in the cluster (using a format of host:port), for example,ha_peers=10.0.0.5:9094,10.0.0.6:9094,10.0.0.7:9094
. You must have at least one (1) Grafana instance added to theha_peers
section. - Set
[ha_listen_address]
to the instance IP address using a format ofhost:port
(or the Pod’s IP in the case of using Kubernetes). By default, it is set to listen to all interfaces (0.0.0.0
). - Set
[ha_peer_timeout]
in the[unified_alerting]
section of the custom.ini to specify the time to wait for an instance to send a notification via the Alertmanager. The default value is 15s, but it may increase if Grafana servers are located in different geographic regions or if the network latency between them is high.
Enable alerting high availability using Redis
As an alternative to Memberlist, you can use Redis for high availability. This is useful if you want to have a central database for HA and cannot support the meshing of all Grafana servers.
- Make sure you have a redis server that supports pub/sub. If you use a proxy in front of your redis cluster, make sure the proxy supports pub/sub.
- In your custom configuration file ($WORKING_DIR/conf/custom.ini), go to the
[unified_alerting]
section. - Set
ha_redis_address
to the redis server address Grafana should connect to. - Optional: Set the username and password if authentication is enabled on the redis server using
ha_redis_username
andha_redis_password
. - 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:
Metric | Description |
---|---|
alertmanager_cluster_messages_received_total | Total number of cluster messages received. |
alertmanager_cluster_messages_received_size_total | Total size of cluster messages received. |
alertmanager_cluster_messages_sent_total | Total number of cluster messages sent. |
alertmanager_cluster_messages_sent_size_total | Total number of cluster messages received. |
alertmanager_cluster_messages_publish_failures_total | Total number of messages that failed to be published. |
alertmanager_cluster_members | Number indicating current number of members in cluster. |
alertmanager_peer_position | Position the Alertmanager instance believes it’s in. The position determines a peer’s behavior in the cluster. |
alertmanager_cluster_pings_seconds | Histogram of latencies for ping messages. |
alertmanager_cluster_pings_failures_total | Total number of failed pings. |
Enable alerting high availability using Kubernetes
You can expose the pod IP through an environment variable via the container definition.
env: - name: POD_IP valueFrom: fieldRef: fieldPath: status.podIP
Add the port 9094 to the Grafana deployment:
ports: - containerPort: 3000 name: http-grafana protocol: TCP - containerPort: 9094 name: grafana-alert protocol: TCP
Add the environment variables to the Grafana deployment:
env: - name: POD_IP valueFrom: fieldRef: fieldPath: status.podIP
Create a headless service that returns the pod IP instead of the service IP, which is what the
ha_peers
need: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
Make sure your grafana deployment has the label matching the selector, e.g.
app:grafana
:Add in the grafana.ini:
[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