---
title: Charmhub | Deploy Canonical Observability Stack Lite using Charmhub - The Open
  Operator Collection
description: Deploy the latest version of Canonical Observability Stack Lite on any
  cloud.
url: https://charmhub.io/cos-lite/docs/how-to/add-alert-rules
---

##### We've discontinued the registration of new Bundles

New Bundle registrations are no longer accepted. Existing bundles remain functional. We recommend using the Juju Terraform Provider for new deployments.

[Learn more](https://discourse.charmhub.io/t/discontinuing-new-charmhub-bundle-registrations/15344)

# Canonical Observability Stack Lite

[Canonical Observability](https://charmhub.io/publisher/observability "View all packages from Canonical Observability")
| bundle

* [Canonical Observability](https://charmhub.io/publisher/observability "View all packages from Canonical Observability")
  | bundle

Platform:

stable 26

```
juju deploy cos-lite
```

[Learn to deploy on juju >](https://juju.is/docs/juju/manage-applications)

---

#### Relevant links

* [Homepage](https://github.com/canonical/cos-lite-bundle)

---

#### Contacts

* [Submit a bug](https://github.com/canonical/cos-lite-bundle/issues)

---

Share your thoughts on this charm with the community on discourse.

[Join the discussion](https://discourse.charmhub.io/)

---

[Add docs to a charm](https://juju.is/docs/sdk/add-docs-to-your-charmhub-page)

Support for providing alert rules through the relation is available for [`loki-k8s`](https://charmhub.io/loki-k8s) and [`prometheus-k8s`](https://charmhub.io/prometheus-k8s), both directly and through intermediary charms like [`grafana-agent-k8s`](https://charmhub.io/grafana-agent-k8s) and [`prometheus-scrape-config-k8s`](https://charmhub.io/prometheus-scrape-config-k8s).

### [Prerequisites](https://charmhub.io/cos-lite/docs/how-to/add-alert-rules#p-21660-prerequisites)

To be able to pass on alert rules, you also need to implement their corresponding telemetry relation interface, as well as instantiating their corresponding library classes. For Prometheus, the relation interface is either `prometheus_scrape` and `MetricsEndpointProvider`, or `prometheus_remote_write` and `RemoteWriteConsumer`. For Loki, this is `loki_push_api` and either `LokiPushApiConsumer` or `LogProxyConsumer`. If both interfaces are implemented, it would roughly look as follows:

```
provides:
  metrics-endpoint:
    interface: prometheus_scrape

requires:
  logging:
    interface: loki_push_api
```

### [Create an alert rule](https://charmhub.io/cos-lite/docs/how-to/add-alert-rules#p-21660-create-an-alert-rule)

An alert rule consists of a name, an expression, a duration, as well as optionally a set of labels and annotations. In this how to, we’ll use an alert rule for `zinc-k8s`. For the sake of this how to, the details of the rule are of less importance. If you want to learn more about crafting alert rules, have a look at the official [Prometheus](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) or [Loki](https://grafana.com/docs/loki/latest/rules/#example) documentation.

```
alert: ZincTargetMissing
expr: up == 0
for: 0m
labels:
  severity: critical
annotations:
  summary: Prometheus target missing (instance {{ $labels.instance }})
  description: |
    A Prometheus target has disappeared. An exporter might be crashed.
    VALUE = {{ $value }}\n LABELS = {{ $labels }}
```

Save the file in `./src/prometheus_alert_rules` for Prometheus, or `./src/loki_alert_rules` for Loki, using a file name ending with `.rule`. Next time you pack and deploy your charm, the alert rules will be transferred over as you integrate it with something using a supported relation interface.

> Note: Custom paths must be passed as an argument to the constructor (e.g. `alert_rules_path=./src/rules/loki`).

---