Clarification on Group Setting for Alerts

Grafana Alerting
1

I’m looking for clarification on the “group” setting for Grafana alerts (v9.3.4)

The official docs say this:

  • For Group, specify a pre-defined group. Newly created rules are appended to the end of the group. Rules within a group are run sequentially at a regular interval, with the same evaluation time.

The interface says:

Rules within the same group are evaluated after the same time interval.

I have a number of questions:

  • “Rules within a group are run sequentially at a regular interval” – does this mean that if I have an alert group with a lot of alerts, that execution of all alerts may take longer than if I had each alert in its own group?
  • “Rules within a group are run sequentially at a regular interval” – what is the delay? Is it predictable, e.g. an alert expression is run every 30 seconds, or does it just depend on the execution of each alert, i.e. after the previous alert is done, the next one starts?
  • “Rules within a group are run … with the same evaluation time.” – does the “evaluate every” property of the alert take precedence over the group setting, or does the group setting take priority?
  • If two alerts within a group fire at the same time, will I get both alerts, or only one?

Thanks in advance for any help.

2

A recent change to the Grafana UI clarified much of my confusion.

Groups are used to determine how frequently rules are evaluated when in a pending state:

Select a group to evaluate all rules in the same group over the same time interval.

And once a group is selected, it tells you what that evaluation period is:

Alert rules in the X group are evaluated every 1m.

Evaluation group interval applies to every rule within a group. It overwrites intervals defined for existing alert rules.

Now, on each alert, you only define how long it is in the pending state for.