Building a hash over an entire set of alerts causes problems, because
the hash differs, on any change, whereas we only want to send
notifications if the alert and it's state have changed. Therefore this
introduces a list of alerts that are active and a list of alerts that
are resolved. If the currently active alerts of a group are a subset of
the ones that have been notified about before then they are
deduplicated. The resolved notifications work the same way, with a
separate list of resolved notifications that have already been sent.
Resolved alerts, even when filtered, have to end up in the
SetNotifiesStage, otherwise when an alert fires again it is ambiguous
whether it was resolved in between or not.
fixes#523
This commit replaces the previous NotifyInfo provider with the new
nflog package. It needs adjustments in the behavior of the deduping
stage.
The nflog stores notification digests per receiver per alert aggregation
group rather than one entry for alert per receiver. This drastically
reduces the number of entries and removes interference
across aggregation groups.
Initial testing has shown BoltDB in plain usage to be a bottleneck
at a few thousand alerts or more (especially JSON decoding.
This commit actually makes them purely memory as a temporary solution.
This commit changes the notification grouping behavior
to simply send all alerts of a group as soon as a single
one of them needs updating.
This fixes a critical bug which caused erroneous resolved
notifications to be sent.
Fabian Reinartz
Frederic Branczyk