operator: initialise default namespaces map config (#5424) (#5426)

(cherry picked from commit 37c40cc)

Co-authored-by: William Dumont <[email protected]>

component/loki/source/kubernetes_events/event_controller.go

@@ -97,7 +97,9 @@ func (ctrl *eventController) runError(ctx context.Context) error {
 	}
 
 	defaultNamespaces := map[string]cache.Config{}
-	defaultNamespaces[ctrl.task.Namespace] = cache.Config{}
+	if ctrl.task.Namespace != "" {
+		defaultNamespaces[ctrl.task.Namespace] = cache.Config{}
+	}
 	opts := cache.Options{
 		Scheme:            scheme,
 		DefaultNamespaces: defaultNamespaces,

component/prometheus/operator/common/crdmanager.go

@@ -243,6 +243,8 @@ func (c *crdManager) runInformers(restConfig *rest.Config, ctx context.Context)
 		return fmt.Errorf("building label selector: %w", err)
 	}
 	for _, ns := range c.args.Namespaces {
+		// TODO: This is going down an unnecessary extra step in the cache when `c.args.Namespaces` defaults to NamespaceAll.
+		// This code path should be simplified and support a scenario when len(c.args.Namespace) == 0.
 		defaultNamespaces := map[string]cache.Config{}
 		defaultNamespaces[ns] = cache.Config{}
 		opts := cache.Options{

pkg/operator/operator.go

@@ -87,7 +87,10 @@ func (c *Config) registerFlags(f *flag.FlagSet) error {
 
 	c.Controller.WebhookServer = webhook.NewServer(webhookServerOptions)
 
-	c.Controller.Cache.DefaultNamespaces[namespace] = cache.Config{}
+	if namespace != "" {
+		c.Controller.Cache.DefaultNamespaces = map[string]cache.Config{}
+		c.Controller.Cache.DefaultNamespaces[namespace] = cache.Config{}
+	}
 
 	// Custom initial values for the endpoint names.
 	c.Controller.ReadinessEndpointName = "/-/ready"