Hide resolved it alert JSON if it was added via timeout

api.go

@@ -78,15 +78,17 @@ func (api *API) addAlerts(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
-	for _, alert := range alerts {
-		now := time.Now()
 
+	now := time.Now()
+
+	for _, alert := range alerts {
 		alert.UpdatedAt = now
 
 		if alert.StartsAt.IsZero() {
 			alert.StartsAt = now
 		}
 		if alert.EndsAt.IsZero() {
+			alert.Timeout = true
 			alert.EndsAt = alert.StartsAt.Add(ResolveTimeout)
 		}
 	}

types/types.go

@@ -32,13 +32,23 @@ type Alert struct {
 	Labels model.LabelSet `json:"labels"`
 
 	// Extra key/value information which does not define alert identity.
-	Annotations Annotations `json:"annotations,omitempty"`
+	Annotations Annotations `json:"annotations"`
 
 	StartsAt time.Time `json:"startsAt,omitempty"`
 	EndsAt   time.Time `json:"endsAt,omitempty"`
 
 	// The authoritative timestamp.
-	UpdatedAt time.Time `json:"timestamp"`
+	UpdatedAt time.Time `json:"-"`
+	Timeout   bool      `json:"-"`
+}
+
+func (a *Alert) MarshalJSON() ([]byte, error) {
+	b := *a
+	if b.Timeout {
+		b.EndsAt = time.Time{}
+	}
+
+	return json.Marshal(b)
 }
 
 // Name returns the name of the alert. It is equivalent to the "alertname" label.