Improve comments around resending resolved alerts (#13990)

Signed-off-by: George Robinson <george.robinson@grafana.com>
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George Robinson 2024-04-25 13:18:50 +01:00 committed by GitHub
parent 4ac78063ee
commit dde2e5eb73
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@ -457,8 +457,17 @@ func (r *AlertingRule) Eval(ctx context.Context, ts time.Time, query QueryFunc,
}
}
// If the alert was previously firing, keep it around for a given
// retention time so it is reported as resolved to the AlertManager.
// If the alert is resolved (was firing but is now inactive) keep it for
// at least the retention period. This is important for a number of reasons:
//
// 1. It allows for Prometheus to be more resilient to network issues that
// would otherwise prevent a resolved alert from being reported as resolved
// to Alertmanager.
//
// 2. It helps reduce the chance of resolved notifications being lost if
// Alertmanager crashes or restarts between receiving the resolved alert
// from Prometheus and sending the resolved notification. This tends to
// occur for routes with large Group intervals.
if a.State == StatePending || (!a.ResolvedAt.IsZero() && ts.Sub(a.ResolvedAt) > resolvedRetention) {
delete(r.active, fp)
}