slimtoolkit/slim · error

no namespaces

Error message

no namespaces

What it means

ensureNamespace resolves the namespace to operate in. When no explicit namespace is given, it falls back to listing all namespaces and using the first one; if the cluster API reports zero namespaces, it fails with 'no namespaces'. An empty namespace list means the API connection is not seeing any cluster content.

Source

Thrown at pkg/app/master/command/debug/handle_kubernetes_runtime.go:636

	names, err := listNamespaces(ctx, api)
	if err != nil {
		log.WithError(err).Error("listNamespaces")
		return nil, err
	}

	return names, nil
}

func ensureNamespace(ctx context.Context, api *kubernetes.Clientset, name string) (string, error) {
	if name == "" {
		namespaces, err := api.CoreV1().Namespaces().List(ctx, metav1.ListOptions{})
		if err != nil {
			return "", err
		}

		if len(namespaces.Items) == 0 {
			return "", fmt.Errorf("no namespaces")
		}

		return namespaces.Items[0].Name, nil
	}

	_, err := api.CoreV1().Namespaces().Get(ctx, name, metav1.GetOptions{})
	if err != nil {
		if apierrors.IsNotFound(err) {
			log.Debugf("ensureNamespace: %s namespace is not found", name)
		}

		return "", err
	}

	return name, nil
}

func listActivePods(ctx context.Context, api *kubernetes.Clientset, nsName string) ([]string, error) {

View on GitHub (pinned to 81940d17fa)

Solutions

1. Pass an explicit namespace to the command so the List fallback is skipped.
2. Check `kubectl config current-context` and `kubectl get namespaces` to confirm you are on the intended cluster and can list namespaces.
3. Fix KUBECONFIG (points to wrong cluster/empty control plane) and retry.
4. Verify RBAC allows listing namespaces; with restrictive RBAC the list may come back empty.

Example fix

// before: relies on auto-detected namespace
slim debug <target>
// after
slim debug <target> --namespace default

ctx=$(kubectl config current-context)
[ "$(kubectl get namespaces -o name | wc -l)" -gt 0 ] || echo "context $ctx sees no namespaces — check kubeconfig"

if err := runDebug(target); err != nil && strings.Contains(err.Error(), "no namespaces") {
    // prompt user to set KUBECONFIG / --namespace
}

When it happens

Trigger: HandleKubernetesRuntime -> ensureNamespace with no namespace name configured; CoreV1().Namespaces().List returns success but an empty Items slice.

Common situations: KUBECONFIG pointing at the wrong cluster or a local mock/proxy that returns empty lists; connecting to a cluster endpoint with a context that has no permissions so list results are filtered to zero; kubeconfig default context changed (e.g., after switching from kind/minikube to a fresh cluster).

Related errors

• no pods
• Pod terminated
• Pod not running
• Container terminated
• malformed Kubernetes workload name

AI-assisted analysis of slimtoolkit/slim@81940d17fa (2026-08-31). Data as JSON: /api/errors/925e34d7cb65b8b5. Report an issue: GitHub.