add exclude namespaces flag

Author: piceri

cmd/deployment-tracker/main.go

@@ -33,18 +33,26 @@ func getEnvOrDefault(key, defaultValue string) string {
 
 func main() {
 	var (
-		kubeconfig  string
-		namespace   string
-		workers     int
-		metricsPort string
+		kubeconfig        string
+		namespace         string
+		excludeNamespaces string
+		workers           int
+		metricsPort       string
 	)
 
 	flag.StringVar(&kubeconfig, "kubeconfig", "", "path to kubeconfig file (uses in-cluster config if not set)")
 	flag.StringVar(&namespace, "namespace", "", "namespace to monitor (empty for all namespaces)")
+	flag.StringVar(&excludeNamespaces, "exclude-namespace", "", "namespace to exclude from monitoring (empty to include all namespaces)")
 	flag.IntVar(&workers, "workers", 2, "number of worker goroutines")
 	flag.StringVar(&metricsPort, "metrics-port", "9090", "port to listen to for metrics")
 	flag.Parse()
 
+	// Cannot use both
+	if namespace != "" && excludeNamespaces != "" {
+		slog.Error("Cannot set both --namespace and --exclude-namespace")
+		os.Exit(1)
+	}
+
 	// Validate worker count
 	if workers < 1 || workers > 100 {
 		slog.Error("Invalid worker count, must be between 1 and 100",
@@ -143,7 +151,7 @@ func main() {
 		cancel()
 	}()
 
-	cntrl, err := controller.New(clientset, namespace, &cntrlCfg)
+	cntrl, err := controller.New(clientset, namespace, excludeNamespaces, &cntrlCfg)
 	if err != nil {
 		slog.Error("Failed to create controller",
 			"error", err)

internal/controller/controller.go

@@ -52,20 +52,9 @@ type Controller struct {
 }
 
 // New creates a new deployment tracker controller.
-func New(clientset kubernetes.Interface, namespace string, cfg *Config) (*Controller, error) {
+func New(clientset kubernetes.Interface, namespace string, excludeNamespaces string, cfg *Config) (*Controller, error) {
 	// Create informer factory
-	var factory informers.SharedInformerFactory
-	if namespace == "" {
-		factory = informers.NewSharedInformerFactory(clientset,
-			30*time.Second,
-		)
-	} else {
-		factory = informers.NewSharedInformerFactoryWithOptions(
-			clientset,
-			30*time.Second,
-			informers.WithNamespace(namespace),
-		)
-	}
+	factory := createInformerFactory(clientset, namespace, excludeNamespaces)
 
 	podInformer := factory.Core().V1().Pods().Informer()
 
@@ -488,6 +477,40 @@ func getCacheKey(dn, digest string) string {
 	return dn + "||" + digest
 }
 
+// createInformerFactory creates a shared informer factory with the given resync period.
+// If excludeNamespaces is non-empty, it will exclude those namespaces from being watched.
+// If namespace is non-empty, it will only watch that namespace.
+func createInformerFactory(clientset kubernetes.Interface, namespace string, excludeNamespaces string) informers.SharedInformerFactory {
+	var factory informers.SharedInformerFactory
+	if namespace != "" {
+		factory = informers.NewSharedInformerFactoryWithOptions(
+			clientset,
+			30*time.Second,
+			informers.WithNamespace(namespace),
+		)
+	} else if excludeNamespaces != "" {
+		excludedNamespacesList := strings.Split(excludeNamespaces, ",")
+		for i := 0; i < len(excludedNamespacesList); i++ {
+			excludedNamespacesList[i] = fmt.Sprintf("metadata.namespace!=%s", strings.TrimSpace(excludedNamespacesList[i]))
+		}
+		tweakListOptions := func(options *metav1.ListOptions) {
+			options.FieldSelector = strings.Join(excludedNamespacesList, ",")
+		}
+
+		factory = informers.NewSharedInformerFactoryWithOptions(
+			clientset,
+			30*time.Second,
+			informers.WithTweakListOptions(tweakListOptions),
+		)
+	} else {
+		factory = informers.NewSharedInformerFactory(clientset,
+			30*time.Second,
+		)
+	}
+
+	return factory
+}
+
 // getARDeploymentName converts the pod's metadata into the correct format
 // for the deployment name for the artifact registry (this is not the same
 // as the K8s deployment's name!