is_resolution built in filter is missing

[nikkictl]

is_resolution logic exists in event.go

sensu-go/api/core/v2/event.go

Line 113 in e3421f7

"is_resolution": e.IsResolution(),

sensu-go/api/core/v2/event.go

Lines 84 to 96 in e3421f7

	func (e *Event) IsResolution() bool {
	if !e.HasCheck() {
	return false
	}
	// Try to retrieve the previous status in the check history and verify if it
	// was a non-zero status, therefore indicating a resolution. The current event
	// has already been added to the check history by eventd so we must retrieve
	// the second to the last
	return (len(e.Check.History) > 1 &&
	e.Check.History[len(e.Check.History)-2].Status != 0 &&
	!e.IsIncident())
	}

but is not implemented in filter.go

sensu-go/backend/pipelined/filter.go

Lines 101 to 128 in 95acb05

	switch filterName {
	case "is_incident":
	// Deny an event if it is neither an incident nor resolution.
	if !event.IsIncident() && !event.IsResolution() {
	logger.WithFields(fields).Debug("denying event that is not an incident/resolution")
	return true
	}
	case "has_metrics":
	// Deny an event if it does not have metrics
	if !event.HasMetrics() {
	logger.WithFields(fields).Debug("denying event without metrics")
	return true
	}
	case "not_silenced":
	// Deny event that is silenced.
	if event.IsSilenced() {
	logger.WithFields(fields).Debug("denying event that is silenced")
	return true
	}
	default:
	// Retrieve the filter from the store with its name
	ctx := types.SetContextFromResource(context.Background(), event.Entity)
	filter, err := p.store.GetEventFilterByName(ctx, filterName)
	if err != nil {
	logger.WithFields(fields).WithError(err).
	Warning("could not retrieve filter")
	return false
	}

We should add the follow case to filter.go so users can invoke the built-in is_resolution filter. We should also document this filter.

case "is_resolution":
    // Deny event that is not a resolution.
    if !event.IsResolution() {
        logger.WithFields(fields).Debug("denying event that is not a resolution")
        return true
    }

[nikkictl]

It appears is_incident filters resolution events, so if that is the preferred terminology, perhaps we should remove the is_resolution key from event.go?

[palourde]

IsResolution() method is used in a couple of places (e.g.

sensu-go/backend/eventd/silenced.go

Line 75 in 15b4e2e

if !event.HasCheck() || !event.IsResolution() {

) and it's not the same as !IsIncident() so I feel like it's still relevant to have that. That being said, maybe it could be exposed as a built-in filter if required.