The stacks don't need to be stored in the manager struct

The map is only ever used in the loop to create and remove stacks, so it
doesn't need to be stored in the struct. This ensures that there can't
be any racy concurrent accesses to it.

Signed-off-by: Tom Wieczorek <twieczorek@mirantis.com>

pkg/applier/manager.go

@@ -38,12 +38,10 @@ type Manager struct {
 	K0sVars           *config.CfgVars
 	KubeClientFactory kubeutil.ClientFactoryInterface
 
-	// client               kubernetes.Interface
 	applier       Applier
 	bundlePath    string
 	cancelWatcher context.CancelFunc
 	log           *logrus.Entry
-	stacks        map[string]stack
 
 	LeaderElector leaderelector.Interface
 }
@@ -62,7 +60,6 @@ func (m *Manager) Init(ctx context.Context) error {
 		return fmt.Errorf("failed to create manifest bundle dir %s: %w", m.K0sVars.ManifestsDir, err)
 	}
 	m.log = logrus.WithField("component", constant.ApplierManagerComponentName)
-	m.stacks = make(map[string]stack)
 	m.bundlePath = m.K0sVars.ManifestsDir
 
 	m.applier = NewApplier(m.K0sVars.ManifestsDir, m.KubeClientFactory)
@@ -120,8 +117,10 @@ func (m *Manager) runWatchers(ctx context.Context) error {
 		return err
 	}
 
+	stacks := make(map[string]stack, len(dirs))
+
 	for _, dir := range dirs {
-		m.createStack(ctx, path.Join(m.bundlePath, dir))
+		m.createStack(ctx, stacks, path.Join(m.bundlePath, dir))
 	}
 
 	for {
@@ -139,27 +138,28 @@ func (m *Manager) runWatchers(ctx context.Context) error {
 			switch event.Op {
 			case fsnotify.Create:
 				if dir.IsDirectory(event.Name) {
-					m.createStack(ctx, event.Name)
+					m.createStack(ctx, stacks, event.Name)
 				}
 			case fsnotify.Remove:
-				m.removeStack(ctx, event.Name)
+				m.removeStack(ctx, stacks, event.Name)
 			}
+
 		case <-ctx.Done():
 			log.Info("manifest watcher done")
 			return nil
 		}
 	}
 }
 
-func (m *Manager) createStack(ctx context.Context, name string) {
+func (m *Manager) createStack(ctx context.Context, stacks map[string]stack, name string) {
 	// safeguard in case the fswatcher would trigger an event for an already existing stack
-	if _, ok := m.stacks[name]; ok {
+	if _, ok := stacks[name]; ok {
 		return
 	}
 
 	stackCtx, cancelStack := context.WithCancel(ctx)
 	stack := stack{cancelStack, NewStackApplier(name, m.KubeClientFactory)}
-	m.stacks[name] = stack
+	stacks[name] = stack
 
 	go func() {
 		log := m.log.WithField("stack", name)
@@ -180,16 +180,16 @@ func (m *Manager) createStack(ctx context.Context, name string) {
 	}()
 }
 
-func (m *Manager) removeStack(ctx context.Context, name string) {
-	stack, ok := m.stacks[name]
+func (m *Manager) removeStack(ctx context.Context, stacks map[string]stack, name string) {
+	stack, ok := stacks[name]
 	if !ok {
 		m.log.
 			WithField("path", name).
 			Debug("attempted to remove non-existent stack, probably not a directory")
 		return
 	}
 
-	delete(m.stacks, name)
+	delete(stacks, name)
 	stack.CancelFunc()
 
 	log := m.log.WithField("stack", name)