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.
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.
This removes the Delete function from the interface as the log
should be append-only and only be reduced by expired entries.
This also adds an argument to configure a background processing routine,
which periodically garbage collects and snapshots.
This adds a new nflog package meant to replace provider.Notifies. It
has a central protobuf type package, which is also meant for usage for
other packages and the API.
The generated Go types are also the in-memory representation.
Fabian Reinartz