Grafana allows you to create alerting rules for an external Grafana Mimir or Loki instance that has ruler API enabled. For information on Grafana Alerting, see [About Grafana Alerting][alerting] which explains the various components of Grafana Alerting. We also recommend that you familiarize yourself with some of the [fundamental concepts][fundamentals] of Grafana Alerting.
- Verify that you have write permission to the Prometheus or Loki data source. Otherwise, you will not be able to create or update Grafana Mimir managed alerting rules.
- **Loki** - The `local` rule storage type, default for the Loki data source, supports only viewing of rules. To edit rules, configure one of the other rule storage types.
- **Grafana Mimir** - use the `/prometheus` prefix. The Prometheus data source supports both Grafana Mimir and Prometheus, and Grafana expects that both the [Query API](/docs/mimir/latest/operators-guide/reference-http-api/#querier--query-frontend) and [Ruler API](/docs/mimir/latest/operators-guide/reference-http-api/#ruler) are under the same URL. You cannot provide a separate URL for the Ruler API.
_Refer to [Add a Grafana Mimir or Loki managed alerting rule]({{< relref "#add-a-grafana-mimir-or-loki-managed-alerting-rule" >}}) (following) for current instructions._
If you do not want to manage alerting rules for a particular Loki or Prometheus data source, go to its settings and clear the **Manage alerts via Alerting UI** checkbox.
- In **Rule name**, add a descriptive name. This name is displayed in the alert rule list. It is also the `alertname` label for every alert instance that is created from this rule.
1. In Step 2, select **Mimir or Loki alert** option.
- Next, select your Loki or Prometheus data source and add the query to evaluate.
- Enter a PromQL or LogQL expression to query. The rule fires if the evaluation result has at least one series with a value that is greater than 0. An alert is created for each series.
- In the **For** text box, specify the duration for which the condition must be true before an alert fires. If you specify `5m`, the condition must be true for 5 minutes before the alert fires.
> **Note:** Once a condition is met, the alert goes into the `Pending` state. If the condition remains active for the duration specified, the alert transitions to the `Firing` state, else it reverts to the `Normal` state.
- From the **Namespace** dropdown, select an existing rule namespace. Otherwise, click **Add new** and enter a name to create a new one. Namespaces can contain one or more rule groups and only have an organizational purpose. For more information, see [Grafana Mimir or Loki rule groups and namespaces][edit-mimir-loki-namespace-group].
- From the **Group** dropdown, select an existing group within the selected namespace. Otherwise, click **Add new** and enter a name to create a new one. Newly created rules are appended to the end of the group. Rules within a group are run sequentially at a regular interval, with the same evaluation time.
