> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chronosphere.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Customize monitor notification messages

<Note>
  This feature isn't available to all Chronosphere Observability Platform users and
  might not be visible in your app. For information about enabling this feature in your
  environment, contact [Chronosphere Support](/support).
</Note>

Use notification templates to control the title and description of
notifications generated by a monitor. Templates are Go template strings
expanded at notification time with alert context, so the notification can
include signal data such as severity, labels, and threshold values.

A notification template has two optional fields:

* Title: The subject line or heading of the notification.
* Description: The body text of the notification.

To add a notification template to a monitor, see
[Create a monitor](/investigate/alerts/monitors#create-a-monitor) or
[Edit a monitor](/investigate/alerts/monitors#edit-a-monitor). For the
`notification_template` field definition, see the
[monitor data model](/investigate/alerts/monitors/data-model#notification-template).

## Set a notification template

Add a `notification_template` block when creating or updating a monitor.

<Tabs>
  <Tab title="Chronoctl" id="notification-template-chronoctl">
    Include a `notification_template` block in your monitor YAML when running
    `chronoctl monitors create` or `chronoctl monitors update`. For more
    information, see [Chronoctl](/tooling/chronoctl).

    ```yaml theme={null}
    notification_template:
      title: "[{{.Severity}}] {{.Labels.service}} — error rate alert"
      description: >-
        Service {{.Labels.service}} in {{.Labels.env}} fired
        {{.ThresholdOp}} {{.Threshold}}. Status: {{.Status}}.
    ```
  </Tab>

  <Tab title="Terraform" id="notification-template-terraform">
    Add a `notification_template` block to your `chronosphere_monitor` resource.
    For more information, see the
    [Terraform provider](/tooling/infrastructure/terraform) documentation.

    ```terraform theme={null}
    resource "chronosphere_monitor" "example" {
      name = "High error rate"

      notification_template {
        title       = "[{{.Severity}}] {{.Labels.service}} — error rate alert"
        description = "Service {{.Labels.service}} in {{.Labels.env}} fired {{.ThresholdOp}} {{.Threshold}}. Status: {{.Status}}."
      }
    }
    ```
  </Tab>

  <Tab title="API" id="notification-template-api">
    Set the `notification_template` field on the monitor body when calling
    [`CreateMonitor`](/tooling/api-info/definition/operations/CreateMonitor)
    or the equivalent update endpoint.

    ```json theme={null}
    {
      "monitor": {
        "name": "High error rate",
        "notification_template": {
          "title": "[{{.Severity}}] {{.Labels.service}} — error rate alert",
          "description": "Service {{.Labels.service}} in {{.Labels.env}} fired {{.ThresholdOp}} {{.Threshold}}. Status: {{.Status}}."
        }
      }
    }
    ```
  </Tab>
</Tabs>

## Error rate alert example

The following template uses severity and label variables to produce a
notification title and description.

```json theme={null}
{
  "title": "[{{.Severity}}] {{.Labels.service}} threshold exceeded",
  "description": "{{.Labels.env}} crossed {{.ThresholdOp}} {{.Threshold}}"
}
```

For a critical alert on the `payments` service in `production`, Chronosphere
Observability Platform renders the notification as:

```text theme={null}
[critical] payments threshold exceeded
production crossed >= 0.95
```

## Template variables

Reference variables with dot notation, for example, `{{.Severity}}`.

| Variable            | Type    | Description                                                                                             |
| ------------------- | ------- | ------------------------------------------------------------------------------------------------------- |
| `.Severity`         | string  | Alert severity: `"critical"` or `"warn"`.                                                               |
| `.Status`           | string  | Alert state: `"firing"` or `"resolved"`.                                                                |
| `.Labels.<name>`    | string  | Signal labels attached to the alert. For example, `.Labels.env` or `.Labels.service`.                   |
| `.Threshold`        | number  | Threshold value for the active severity condition.                                                      |
| `.ThresholdOp`      | string  | Comparison operator for the active condition. For example, `">="` or `"<"`.                             |
| `.ResolveThreshold` | number  | Effective resolve threshold. Defaults to `.Threshold` when no separate resolve threshold is configured. |
| `.StartsAtEpoch`    | integer | Start time of the earliest alert in `.Alerts`, in epoch milliseconds.                                   |
| `.Alerts`           | list    | All alerts in the notification group. See [Alert object fields](#alert-object-fields).                  |
| `.Alerts.Firing`    | list    | Subset of `.Alerts` that are currently firing.                                                          |
| `.Alerts.Resolved`  | list    | Subset of `.Alerts` that have resolved.                                                                 |

### Alert object fields

Each item in `.Alerts`, `.Alerts.Firing`, and `.Alerts.Resolved` exposes the
following fields:

| Field               | Type      | Description                              |
| ------------------- | --------- | ---------------------------------------- |
| `.Status`           | string    | Alert state: `"firing"` or `"resolved"`. |
| `.Labels`           | map       | Per-alert label key/value pairs.         |
| `.Annotations`      | map       | Per-alert annotation key/value pairs.    |
| `.Threshold`        | number    | Per-alert threshold value.               |
| `.ThresholdOp`      | string    | Per-alert comparison operator.           |
| `.ResolveThreshold` | number    | Per-alert effective resolve threshold.   |
| `.StartsAt`         | timestamp | Time the alert started firing.           |
| `.EndsAt`           | timestamp | Time the alert resolved, if applicable.  |

## Template functions

In addition to the standard Go template built-ins, the following functions are
available.

### Arithmetic

| Function | Description              | Example                    |
| -------- | ------------------------ | -------------------------- |
| `add`    | Adds two integers.       | `{{add 1 2}}` returns `3`  |
| `sub`    | Subtracts two integers.  | `{{sub 5 3}}` returns `2`  |
| `mul`    | Multiplies two integers. | `{{mul 3 4}}` returns `12` |

### String manipulation

| Function       | Description                                              | Example                                        |
| -------------- | -------------------------------------------------------- | ---------------------------------------------- |
| `toUpper`      | Converts a string to uppercase.                          | `{{toUpper .Labels.env}}` returns `PRODUCTION` |
| `toLower`      | Converts a string to lowercase.                          | `{{toLower .Labels.env}}` returns `production` |
| `title`        | Title-cases a string.                                    | `{{title .Labels.env}}` returns `Production`   |
| `join`         | Joins a string slice with a separator.                   | `{{join .Labels.regions ", "}}`                |
| `match`        | Returns `true` if a string matches a regular expression. | `{{match "^prod" .Labels.env}}`                |
| `reReplaceAll` | Replaces all regexp matches in a string.                 | `{{reReplaceAll "-" "_" .Labels.service}}`     |

## Template examples

### Count firing and resolved alerts

```text theme={null}
{{len .Alerts.Firing}} firing, {{len .Alerts.Resolved}} resolved
```

### List all firing alerts

```text theme={null}
{{range .Alerts.Firing -}}
- {{.Labels.service}} ({{.Labels.env}})
{{end}}
```

### Show the resolve threshold conditionally

```text theme={null}
Threshold: {{.ThresholdOp}} {{.Threshold}}
{{- if ne .ResolveThreshold .Threshold}} (resolves at {{.ResolveThreshold}}){{end}}
```

### Reference the alert start time

```text theme={null}
Alert started at epoch ms: {{.StartsAtEpoch}}
```