fix: Improve namespace validation logic for update, inspect command

cmd/nerdctl/namespace/namespace_update.go

@@ -36,7 +36,8 @@ func updateCommand() *cobra.Command {
 		SilenceUsage:      true,
 		SilenceErrors:     true,
 	}
-	cmd.Flags().StringArrayP("label", "l", nil, "Set labels for a namespace")
+	cmd.Flags().StringArrayP("label", "l", nil, "Set labels for a namespace (required)")
+	cmd.MarkFlagRequired("label")
 	return cmd
 }
 

pkg/cmd/namespace/common.go

@@ -16,7 +16,16 @@
 
 package namespace
 
-import "strings"
+import (
+	"context"
+	"fmt"
+	"slices"
+	"strings"
+
+	"github.com/compose-spec/compose-go/v2/errdefs"
+
+	"github.com/containerd/containerd/v2/pkg/namespaces"
+)
 
 func objectWithLabelArgs(args []string) map[string]string {
 	if len(args) >= 1 {
@@ -39,3 +48,16 @@ func labelArgs(labelStrings []string) map[string]string {
 
 	return labels
 }
+
+// namespaceExists checks if the namespace exists
+func namespaceExists(ctx context.Context, store namespaces.Store, namespace string) error {
+	nsList, err := store.List(ctx)
+	if err != nil {
+		return err
+	}
+	if slices.Contains(nsList, namespace) {
+		return nil
+	}
+
+	return fmt.Errorf("namespace %s: %w", namespace, errdefs.ErrNotFound)
+}

pkg/cmd/namespace/inspect.go

@@ -21,25 +21,39 @@ import (
 
 	containerd "github.com/containerd/containerd/v2/client"
 	"github.com/containerd/containerd/v2/pkg/namespaces"
+	"github.com/containerd/log"
 
 	"github.com/containerd/nerdctl/v2/pkg/api/types"
 	"github.com/containerd/nerdctl/v2/pkg/formatter"
 	"github.com/containerd/nerdctl/v2/pkg/inspecttypes/native"
 )
 
 func Inspect(ctx context.Context, client *containerd.Client, inspectedNamespaces []string, options types.NamespaceInspectOptions) error {
-	result := make([]interface{}, len(inspectedNamespaces))
-	for index, ns := range inspectedNamespaces {
+	result := []interface{}{}
+	warns := []error{}
+
+	for _, ns := range inspectedNamespaces {
 		ctx = namespaces.WithNamespace(ctx, ns)
-		labels, err := client.NamespaceService().Labels(ctx, ns)
+		namespaceService := client.NamespaceService()
+		if err := namespaceExists(ctx, namespaceService, ns); err != nil {
+			warns = append(warns, err)
+			continue
+		}
+		labels, err := namespaceService.Labels(ctx, ns)
 		if err != nil {
 			return err
 		}
 		nsInspect := native.Namespace{
 			Name:   ns,
 			Labels: &labels,
 		}
-		result[index] = nsInspect
+		result = append(result, nsInspect)
+	}
+	if err := formatter.FormatSlice(options.Format, options.Stdout, result); err != nil {
+		return err
+	}
+	for _, warn := range warns {
+		log.G(ctx).Warn(warn)
 	}
-	return formatter.FormatSlice(options.Format, options.Stdout, result)
+	return nil
 }

pkg/cmd/namespace/update.go

@@ -27,6 +27,9 @@ import (
 func Update(ctx context.Context, client *containerd.Client, namespace string, options types.NamespaceUpdateOptions) error {
 	labelsArg := objectWithLabelArgs(options.Labels)
 	namespaces := client.NamespaceService()
+	if err := namespaceExists(ctx, namespaces, namespace); err != nil {
+		return err
+	}
 	for k, v := range labelsArg {
 		if err := namespaces.SetLabel(ctx, namespace, k, v); err != nil {
 			return err