feat: Add configuration option to scope application listing / getting to particular namespace

cmd/main.go

@@ -31,6 +31,7 @@ type ImageUpdaterConfig struct {
 	ApplicationsAPIKind    string
 	ClientOpts             argocd.ClientOptions
 	ArgocdNamespace        string
+	AppNamespace           string
 	DryRun                 bool
 	CheckInterval          time.Duration
 	ArgoClient             argocd.ArgoCD

cmd/run.go

@@ -24,6 +24,8 @@ import (
 	"github.com/spf13/cobra"
 
 	"golang.org/x/sync/semaphore"
+
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
 // newRunCommand implements "run" command
@@ -235,6 +237,7 @@ func newRunCommand() *cobra.Command {
 	runCmd.Flags().BoolVar(&disableKubernetes, "disable-kubernetes", false, "do not create and use a Kubernetes client")
 	runCmd.Flags().IntVar(&cfg.MaxConcurrency, "max-concurrency", 10, "maximum number of update threads to run concurrently")
 	runCmd.Flags().StringVar(&cfg.ArgocdNamespace, "argocd-namespace", "", "namespace where ArgoCD runs in (current namespace by default)")
+	runCmd.Flags().StringVar(&cfg.AppNamespace, "application-namespace", v1.NamespaceAll, "namespace where Argo Image Updater will manage applications (all namespaces by default)")
 	runCmd.Flags().StringSliceVar(&cfg.AppNamePatterns, "match-application-name", nil, "patterns to match application name against")
 	runCmd.Flags().StringVar(&cfg.AppLabel, "match-application-label", "", "label selector to match application labels against")
 	runCmd.Flags().BoolVar(&warmUpCache, "warmup-cache", true, "whether to perform a cache warm-up on startup")
@@ -256,7 +259,7 @@ func runImageUpdater(cfg *ImageUpdaterConfig, warmUp bool) (argocd.ImageUpdaterR
 	var argoClient argocd.ArgoCD
 	switch cfg.ApplicationsAPIKind {
 	case applicationsAPIKindK8S:
-		argoClient, err = argocd.NewK8SClient(cfg.KubeClient)
+		argoClient, err = argocd.NewK8SClient(cfg.KubeClient, &argocd.K8SClientOptions{AppNamespace: cfg.AppNamespace})
 	case applicationsAPIKindArgoCD:
 		argoClient, err = argocd.NewAPIClient(&cfg.ClientOpts)
 	default:

docs/install/reference.md

@@ -26,6 +26,10 @@ Runs the Argo CD Image Updater, possibly in an endless loop.
 
 ### Flags
 
+**--application-namespace *namespace***
+
+Specifies the Kubernetes namespace in which Argo CD Image Updater will manage Argo CD Applications when using the Kubernetes-based Application API. By default, applications in all namespaces are considered. This flag can be used to limit scope to a single namespace for performance, security, or organizational reasons.
+
 **--argocd-auth-token *token***
 
 Use *token* for authenticating to the Argo CD API. This token must be a base64

pkg/argocd/argocd.go

@@ -25,13 +25,21 @@ import (
 
 // Kubernetes based client
 type k8sClient struct {
-	kubeClient *kube.ImageUpdaterKubernetesClient
+	kubeClient   *kube.ImageUpdaterKubernetesClient
+	appNamespace *string
 }
 
-// GetApplication retrieves an application by name across all namespaces.
+// GetApplication retrieves an application by name, either in a specific namespace or all namespaces depending on client configuration.
 func (client *k8sClient) GetApplication(ctx context.Context, appName string) (*v1alpha1.Application, error) {
-	// List all applications across all namespaces (using empty labelSelector)
-	appList, err := client.ListApplications(v1.NamespaceAll)
+	// List all applications across configured namespace or all namespaces (using empty labelSelector)
+	if *client.appNamespace != v1.NamespaceAll {
+		return client.kubeClient.ApplicationsClientset.ArgoprojV1alpha1().Applications(*client.appNamespace).Get(ctx, appName, v1.GetOptions{})
+	}
+	return client.getApplicationInAllNamespaces(appName)
+}
+
+func (client *k8sClient) getApplicationInAllNamespaces(appName string) (*v1alpha1.Application, error) {
+	appList, err := client.ListApplications("")
 	if err != nil {
 		return nil, fmt.Errorf("error listing applications: %w", err)
 	}
@@ -61,7 +69,7 @@ func (client *k8sClient) GetApplication(ctx context.Context, appName string) (*v
 
 // ListApplications lists all applications across all namespaces.
 func (client *k8sClient) ListApplications(labelSelector string) ([]v1alpha1.Application, error) {
-	list, err := client.kubeClient.ApplicationsClientset.ArgoprojV1alpha1().Applications(v1.NamespaceAll).List(context.TODO(), v1.ListOptions{LabelSelector: labelSelector})
+	list, err := client.kubeClient.ApplicationsClientset.ArgoprojV1alpha1().Applications(*client.appNamespace).List(context.TODO(), v1.ListOptions{LabelSelector: labelSelector})
 	if err != nil {
 		return nil, fmt.Errorf("error listing applications: %w", err)
 	}
@@ -99,9 +107,23 @@ func (client *k8sClient) UpdateSpec(ctx context.Context, spec *application.Appli
 	return nil, fmt.Errorf("max retries(%d) reached while updating application: %s", maxRetries, spec.GetName())
 }
 
+type K8SClientOptions struct {
+	AppNamespace string
+}
+
 // NewK8SClient creates a new kubernetes client to interact with kubernetes api-server.
-func NewK8SClient(kubeClient *kube.ImageUpdaterKubernetesClient) (ArgoCD, error) {
-	return &k8sClient{kubeClient: kubeClient}, nil
+func NewK8SClient(kubeClient *kube.ImageUpdaterKubernetesClient, opts *K8SClientOptions) (ArgoCD, error) {
+	// Provide default options if nil
+	if opts == nil {
+		opts = &K8SClientOptions{
+			AppNamespace: v1.NamespaceAll,
+		}
+	}
+
+	return &k8sClient{
+		kubeClient:   kubeClient,
+		appNamespace: &opts.AppNamespace,
+	}, nil
 }
 
 // Native

pkg/argocd/argocd_test.go

@@ -1023,7 +1023,7 @@ func TestKubernetesClient(t *testing.T) {
 			Namespace: "testns1",
 		},
 		ApplicationsClientset: fake.NewSimpleClientset(app1, app2),
-	})
+	}, nil)
 
 	require.NoError(t, err)
 
@@ -1064,7 +1064,7 @@ func TestKubernetesClient(t *testing.T) {
 		// Create the Kubernetes client
 		client, err := NewK8SClient(&kube.ImageUpdaterKubernetesClient{
 			ApplicationsClientset: clientset,
-		})
+		}, nil)
 		require.NoError(t, err)
 
 		// Test ListApplications error handling
@@ -1094,7 +1094,7 @@ func TestKubernetesClient(t *testing.T) {
 		// Create the Kubernetes client
 		client, err := NewK8SClient(&kube.ImageUpdaterKubernetesClient{
 			ApplicationsClientset: clientset,
-		})
+		}, nil)
 		require.NoError(t, err)
 
 		// Test GetApplication with multiple matching applications
@@ -1124,7 +1124,7 @@ func TestKubernetesClientUpdateSpec(t *testing.T) {
 
 		client, err := NewK8SClient(&kube.ImageUpdaterKubernetesClient{
 			ApplicationsClientset: clientset,
-		})
+		}, nil)
 		require.NoError(t, err)
 
 		appName := "test-app"
@@ -1145,7 +1145,7 @@ func TestKubernetesClientUpdateSpec(t *testing.T) {
 
 		client, err := NewK8SClient(&kube.ImageUpdaterKubernetesClient{
 			ApplicationsClientset: clientset,
-		})
+		}, nil)
 		require.NoError(t, err)
 
 		appName := "test-app"
@@ -1169,7 +1169,7 @@ func TestKubernetesClientUpdateSpec(t *testing.T) {
 
 		client, err := NewK8SClient(&kube.ImageUpdaterKubernetesClient{
 			ApplicationsClientset: clientset,
-		})
+		}, nil)
 		require.NoError(t, err)
 
 		clientset.PrependReactor("update", "applications", func(action k8stesting.Action) (handled bool, ret runtime.Object, err error) {
@@ -1198,7 +1198,7 @@ func TestKubernetesClientUpdateSpec(t *testing.T) {
 
 		client, err := NewK8SClient(&kube.ImageUpdaterKubernetesClient{
 			ApplicationsClientset: clientset,
-		})
+		}, nil)
 		require.NoError(t, err)
 
 		clientset.PrependReactor("update", "applications", func(action k8stesting.Action) (handled bool, ret runtime.Object, err error) {