Don't federate stale samples

web/federate.go

@@ -46,11 +46,13 @@ func (h *Handler) federation(w http.ResponseWriter, req *http.Request) {
 		}
 	}
 
-	format := expfmt.Negotiate(req.Header)
+	var (
+		minTimestamp = model.Now().Add(-promql.StalenessDelta)
+		format       = expfmt.Negotiate(req.Header)
+		enc          = expfmt.NewEncoder(w, format)
+	)
 	w.Header().Set("Content-Type", string(format))
 
-	enc := expfmt.NewEncoder(w, format)
-
 	protMetric := &dto.Metric{
 		Label:   []*dto.LabelPair{},
 		Untyped: &dto.Untyped{},
@@ -64,7 +66,8 @@ func (h *Handler) federation(w http.ResponseWriter, req *http.Request) {
 		globalUsed := map[model.LabelName]struct{}{}
 
 		sp := h.storage.LastSamplePairForFingerprint(fp)
-		if sp == nil {
+		// Discard if sample does not exist or lays before the staleness interval.
+		if sp == nil || sp.Timestamp.Before(minTimestamp) {
 			continue
 		}
 

web/ui/bindata.go

@@ -134,7 +134,7 @@ func webUiTemplatesAlertsHtml() (*asset, error) {
 		return nil, err
 	}
 
-	info := bindataFileInfo{name: "web/ui/templates/alerts.html", size: 1707, mode: os.FileMode(420), modTime: time.Unix(1448976906, 0)}
+	info := bindataFileInfo{name: "web/ui/templates/alerts.html", size: 1707, mode: os.FileMode(420), modTime: time.Unix(1450269200, 0)}
 	a := &asset{bytes: bytes, info: info}
 	return a, nil
 }