vmalert: add template variable to hold the "for:" alert rule value

[rcowham]

It would be nice to be able to include

  - alert: InstanceDown
    expr: up == 0
    for: 5m
    labels:
      severity: page
    annotations:
      description: '{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes.'
      summary: 'Instance {{ $labels.instance }} down'

E.g. allow something like this:

      description: '{{ $labels.instance }} of job {{ $labels.job }} has been down for more than {{ $for }}.'

Thoughts?

[f41gh7]

Hello, it should be already possible to use the value of for field from alerting rule, in this case it should be 5m.

For the actual firing state of alert, it's recommended to use value of StartsAt field at alertmanager

https://prometheus.io/docs/alerting/latest/notifications/#alert

[rcowham]

Apologies - but at the link you gave I am not seeing "for" as an option. Should I raise it with prometheus guys?