Frontend alerts

RUM data is stored as ordinary logs, so frontend alerts are ordinary logs-based alert rules. Three templates fill the query, the condition and the name for you; you only pick a notification channel and save. Creating and editing rules needs the Admin or Editor role.

Use them when you want to know, without watching the screens, that pages became slow, that more users hit errors, or that one particular error came back.

The templates

Template	Fires when	Query	Condition
LCP p75 above 2.5 s	Largest Contentful Paint gets slow, one alert per route.	p75(browser.web_vital.value) of browser.web_vital events with browser.web_vital.name = 'lcp', grouped by fusescope.rum.view.route	ABOVE 2.5 s ALL THE TIME
Session error rate above 5%	More than 5% of sessions hit a JavaScript error.	A: sessions with an exception event; B: all sessions (both count_distinct(session.id)); formula F1 = A / B * 100	ABOVE 5% AT LEAST ONCE
JS errors above 10	More than 10 errors in the evaluation window.	count() of exception events	ABOVE 10 IN TOTAL

Every template is filtered to one application with fusescope.rum.application.id. Change the values freely before saving: the threshold, the route, or Group By service.version to get one alert per release. With the default evaluation window, Last 5 minutes, JS errors above 10 means more than 10 errors in 5 minutes. See Conditions for what ALL THE TIME, AT LEAST ONCE and IN TOTAL mean.

Start from a template

From anywhere, open Alerts, click New Alert and choose Log-based Alert. When you have RUM applications, a Start from a frontend template panel sits above the query:

1. Rule name: filled from the application and the template, such as shop-demo LCP p75 above 2.5 s on /. Rename it as you like.
2. Start from a frontend template fills the query, the condition and the name.
3. Application: the RUM application the rule watches.
4. The templates; the selected one is highlighted. Picking another replaces the query.
5. The query the template wrote, here LCP events of shop-demo on the route /.
6. How this maps to frontend data: which events and attributes each part of the query reads, and tips such as keeping the LCP alert to routes with about 50 page loads in the window, since a p75 of a few loads is noisy.

Then set the notification channel in Notification settings and click Save Alert Rule. The rule then behaves like any other; see Alert rules.

Start from the RUM screens

The RUM screens open the same editor with the template already applied:

• Create alert in an application’s header offers the three templates for that application. LCP p75 above 2.5 s is grouped by route, so each route alerts on its own.

  

• Create alert in a route’s detail starts LCP p75 above 2.5 s filtered to that route.

• Alert on this error in an error’s detail starts JS errors above 10 filtered to that exception type and message.

Note

Nothing is saved until you click Save Alert Rule. Close the editor to discard the draft.

Example: be told when a release slows a page

1. Open the route. In Views, click the route your users land on, such as /.

2. Create the alert. Click Create alert in the sheet. The editor opens with shop-demo LCP p75 above 2.5 s on /.

3. Check the preview. The chart under the query draws the route’s LCP p75 with the 2.5 s threshold as a dashed line. If the line is far below it, the threshold is right.

4. Choose who is told. In Notification settings, pick a channel, such as slack-oncall, and click Save Alert Rule.

Related

• Alert rules
• Notification channels
• Views