Label bootstrap instances on an update (#405)

Fix #404

Signed-off-by: David Gageot <david@gageot.net>

Author: dgageot

pkg/plugin/group/quorum.go

@@ -70,7 +70,7 @@ func (q *quorum) Size() uint {
 }
 
 func (q *quorum) converge() {
-	descriptions, err := q.scaled.List()
+	descriptions, err := labelAndList(q.scaled)
 	if err != nil {
 		log.Errorf("Failed to check group: %s", err)
 		return

pkg/plugin/group/rollingupdate.go

@@ -61,7 +61,7 @@ func (r *rollingupdate) waitUntilQuiesced(pollInterval time.Duration, expectedNe
 			//   - instances with the desired config are healthy
 
 			// TODO(wfarner): Get this information from the scaler to reduce redundant network calls.
-			instances, err := r.scaled.List()
+			instances, err := labelAndList(r.scaled)
 			if err != nil {
 				return err
 			}
@@ -116,7 +116,7 @@ func (r *rollingupdate) waitUntilQuiesced(pollInterval time.Duration, expectedNe
 // TODO(wfarner): Make this routine more resilient to transient errors.
 func (r *rollingupdate) Run(pollInterval time.Duration) error {
 
-	instances, err := r.scaled.List()
+	instances, err := labelAndList(r.scaled)
 	if err != nil {
 		return err
 	}
@@ -133,7 +133,7 @@ func (r *rollingupdate) Run(pollInterval time.Duration) error {
 		}
 		log.Info("Scaler has quiesced")
 
-		instances, err := r.scaled.List()
+		instances, err := labelAndList(r.scaled)
 		if err != nil {
 			return err
 		}

pkg/plugin/group/scaled.go

@@ -153,6 +153,23 @@ func (s *scaledGroup) Label() error {
 	return nil
 }
 
+func labelAndList(scaled Scaled) ([]instance.Description, error) {
+	descriptions, err := scaled.List()
+	if err != nil {
+		return nil, err
+	}
+
+	if !needsLabel(descriptions) {
+		return descriptions, nil
+	}
+
+	if err := scaled.Label(); err != nil {
+		return nil, err
+	}
+
+	return scaled.List()
+}
+
 func needsLabel(instances []instance.Description) bool {
 	for _, inst := range instances {
 		if instanceNeedsLabel(inst) {

pkg/plugin/group/scaler.go

@@ -35,7 +35,7 @@ func (s *scaler) PlanUpdate(scaled Scaled, settings groupSettings, newSettings g
 
 	sizeChange := int(newSettings.config.Allocation.Size) - int(settings.config.Allocation.Size)
 
-	instances, err := scaled.List()
+	instances, err := labelAndList(s.scaled)
 	if err != nil {
 		return nil, err
 	}
@@ -220,26 +220,12 @@ func (s *scaler) waitIfReachParallelLimit(current int, batch *sync.WaitGroup) {
 }
 
 func (s *scaler) converge() {
-	descriptions, err := s.scaled.List()
+	descriptions, err := labelAndList(s.scaled)
 	if err != nil {
 		log.Errorf("Failed to list group instances: %s", err)
 		return
 	}
 
-	if needsLabel(descriptions) {
-		err := s.scaled.Label()
-		if err != nil {
-			log.Errorf("Failed to label the group instances: %s", err)
-			return
-		}
-
-		descriptions, err = s.scaled.List()
-		if err != nil {
-			log.Errorf("Failed to list group instances: %s", err)
-			return
-		}
-	}
-
 	log.Debugf("Found existing instances: %v", descriptions)
 
 	grp := sync.WaitGroup{}