Can we add a dynamic label to a Grafana alert?

Question

I am using Grafana 9.4 for dashboarding and alerting. I currently have an alert set up with:

• Query A:
  • a Prometheus metric with labels like {tenant="tenant1", ...} and legend set to {{tenant}}.
• Expression B (the alert condition):
  • Classic_conditions WHEN last() of A is above 100

When triggering, the alert currently generates a notification similar to:

Firing
Value: B0=222.28333333333333
Labels:
- alertname = My alert name
- grafana_folder = My folder
- team = my-team
Annotations:
- summary = My summary
...

1. Would it be possible to have a dynamic label that would contain my tenant's name? That way, I could silence the alert for a given tenant only? I tried a few values for the label thinking that some sort of templating was used but I couldn't get the proper syntax to have a value.
2. How can I at least replace the B0 in the notification with the actual tenant name from query A?

Answer 1

You have to use Grafana unified alerting (not old Grafana legacy alerting).

1. A: use query, which will group by tenant label
2. B: use expression with Operation: Reduce, Function: Last
3. C: use expression with Operation: Math, Expression: $B>100

Set alert condition: C - expression.

Use Preview alerts to verify that all labels are generated correctly.

Tenant label will be available in the alert labels section. Of course you can use it as {{ $labels.B.tenant}} in the alert Description or Summary field.