cache previously created signal groups better for potential re-use

service/integration/signal/sender.go

@@ -45,10 +45,16 @@ func (s *Sender) CreateDefaultSignalSubscription(appName string) (*notification.
 		return nil, err
 	}
 
-	return &notification.SignalSubscription{
+	signalSub := &notification.SignalSubscription{
 		GroupID: groupID,
 		Account: account,
-	}, nil
+	}
+
+	if err := s.store.SaveSignalGroup(appName, signalSub); err != nil {
+		s.logger.Warn("Failed to cache Signal group", "error", err)
+	}
+
+	return signalSub, nil
 }
 
 func (s *Sender) Send(sub *notification.Subscription, notif notification.Notification) error {

service/notification/dispatcher.go

@@ -104,8 +104,7 @@ func (d *Dispatcher) Send(appName string, notif Notification) error {
 	for _, sub := range app.Subscriptions {
 		sender, ok := d.senders[sub.Channel]
 		if !ok {
-			d.logger.Error("No sender for channel", "channel", sub.Channel, "subscriptionID", sub.ID)
-			lastErr = fmt.Errorf("no sender for channel: %s", sub.Channel)
+			d.logger.Debug("Skipping subscription for disabled channel", "channel", sub.Channel, "subscriptionID", sub.ID)
 			continue
 		}
 
@@ -195,9 +194,21 @@ func (d *Dispatcher) trySignalAutoConfig(appName string) (*App, error) {
 		return nil, fmt.Errorf("sender does not implement signal auto-configuration")
 	}
 
-	signalSub, err := autoConfigurer.CreateDefaultSignalSubscription(appName)
+	var signalSub *SignalSubscription
+
+	cachedGroup, err := d.store.GetSignalGroup(appName)
 	if err != nil {
-		return nil, err
+		d.logger.Warn("Failed to check for cached Signal group", "error", err)
+	}
+
+	if cachedGroup != nil {
+		d.logger.Debug("Reusing cached Signal group", "app", appName)
+		signalSub = cachedGroup
+	} else {
+		signalSub, err = autoConfigurer.CreateDefaultSignalSubscription(appName)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	subID, err := GenerateSubscriptionID()

service/server/handlers_subscriptions.go

@@ -104,10 +104,6 @@ func (s *Server) handleCreateSubscription(w http.ResponseWriter, r *http.Request
 					return
 				}
 				sub.Signal = signalSub
-
-				if err := s.store.SaveSignalGroup(appName, signalSub); err != nil {
-					s.logger.Warn("Failed to cache Signal group", "error", err)
-				}
 			}
 		}