An alert reports state changes by sending notifications to one or more alert targets. Each notification contains information extracted from the alert about its state change.
The timing of an alert notification depends on the alert target:
- For simple targets (email addresses and PagerDuty keys added directly in the alert’s Target List), a notification is sent whenever the alert is firing, updated, resolved, snoozed or in a maintenance window.
- For custom alert targets, a notification is sent in response to each triggering event that is specified for the target.
Sample Alert Notification
If you have specified your email address as the alert target, you receive an email like the following whenever the alert fires:
Chart Images in Alert Notifications
When an alert starts firing or is updated, the resulting alert notification can include an image of a chart showing data at the time the alert was triggered. The sample email notification above includes the following chart image:
Chart images show the results of an alert’s display expression. If you have set the alert’s Display Expression field, the chart image provides a snapshot of the time series being tested by the alert.
A chart image is a static snapshot that captures the state of the data at the time the alert was triggered. Such a snapshot can be helpful for diagnosing a possible misfiring alert, because the chart image can show you the exact state of the data that caused the alert to fire. (In contrast, an interactive chart viewed through the notification shows the data at the time you bring up the chart, which might include data that was backfilled after a delay.)
For performance reasons, a chart image is included only if the alert’s conditional query takes a minute or less to return. The chart image can take a few seconds to create, so you might briefly see a placeholder image in the notification.
Chart images are automatically included in notifications for:
- Simple alert targets (email addresses and PagerDuty keys that are added directly in the alert’s target list).
- Custom alert targets for PagerDuty notifications.
- (Version 2018-26.x and later) Predefined templates for custom HTML email targets and for Slack targets.
You can optionally include chart images in notifications for custom alert targets for other messaging platforms.
Note If you created a custom alert target before 2018-26.x and you want to include chart images in notifications to that target, you must edit the alert target’s template. See Adding Chart Images to Older Custom Alert Targets for sample setup instructions for updating an email alert target.
(Version 2018-26.x and later) You exclude chart images from notifications to custom HTML email or Slack targets by removing the corresponding variable from their templates. You cannot remove chart images from custom PagerDuty alert targets.
Interactive Charts Linked by Alert Notifications
An alert notification includes a URL that links to an interactive chart showing data at the time the alert was triggered. The sample email notification above displays the URL as a View Alert button that you can click to see the following interactive chart:
The interactive chart viewed through an alert notification shows the results of the alert’s display expression. If you have set the alert’s Display Expression field, the interactive chart shows the time series being tested by the alert. Depending on the state change that triggered the alert, the interactive chart can display additional queries for alert events and alert metrics:
- <Alert name> - The display expression if one was specified. Otherwise, the condition expression.
- Alert Condition - The condition expression, if the display expression is shown.
- Alert Firings - An events() query that shows events of type
alertfor the alert. These system events occur whenever the alert is opened. The query shows both the current firing (an ongoing event) and any past firings (ended events).
- Alert Details - An events() query that shows events of type
alert-detailfor the alert. These system events occur whenever the alert is updated (continues firing while an individual time series changes from recovered to failing, or from failing to recovered).
- Alert Data - A query for alert metrics. These metrics are shown when the alert is open or updated.
Interactive charts enable you to investigate your data by performing additional queries, changing the time window, and so on.
Note that interactive charts always show the current state of your data as of the time you bring up the chart, which could be somewhat later than the event that triggered the alert. Consequently, although the interactive chart is set to a custom date showing the time window in which the alert was triggered, it could be backfilled with data values that were reported during that time window, but were not ingested until later. The presence of delayed and then backfilled data could obscure the reason why the alert fired. If you suspect a misfiring alert, you can inspect a chart image included in the notification.
If you use the out-of-the-box PagerDuty alert target, and you resolve the incident in PagerDuty while the alert is still firing in Wavefront, two scenarios are possible:
If there is a change to the set of sources being affected, that change triggers a new incident in PagerDuty. Changes to the set of sources being affected include:
- Newly affected sources are added to the list of existing affected sources
- A subset of the existing sources being affected is no longer affected
If all affected sources are no longer affected and the alert is resolved in Wavefront, then no new incident is logged into PagerDuty.
You can customize this behavior by creating a custom PagerDuty alert target with different triggers.