GoogleContainerTools/skaffold · error

cannot parse the namespace template on user defined port for

Error message

cannot parse the namespace template on user defined port forwarder: %w

What it means

applyWithTemplate expands environment-variable templates in user-defined port-forward resources. If the namespace field contains an invalid template (e.g. unbalanced braces or a missing env var), ExpandEnvTemplateOrFail fails and the error is wrapped with "cannot parse the namespace template on user defined port forwarder".

Source

Thrown at pkg/skaffold/kubernetes/portforward/resource_forwarder.go:115

	}

	var serviceResources []*latest.PortForwardResource
	if p.services {
		found, err := retrieveServices(ctx, p.label, namespaces, p.kubeContext)
		if err != nil {
			return fmt.Errorf("retrieving services for automatic port forwarding: %w", err)
		}
		serviceResources = found
	}
	p.portForwardResources(ctx, append(p.userDefinedResources, serviceResources...))
	return nil
}

func applyWithTemplate(resource *latest.PortForwardResource) error {
	if resource.Namespace != "" {
		namespace, err := util.ExpandEnvTemplateOrFail(resource.Namespace, nil)
		if err != nil {
			return fmt.Errorf("cannot parse the namespace template on user defined port forwarder: %w", err)
		}
		resource.Namespace = namespace
	}
	name, err := util.ExpandEnvTemplateOrFail(resource.Name, nil)
	if err != nil {
		return fmt.Errorf("cannot parse the name template on user defined port forwarder: %w", err)
	}
	resource.Name = name
	return nil
}

func (p *ResourceForwarder) Stop() {
	p.entryManager.Stop()
}

// Port forward each resource individually in a goroutine
func (p *ResourceForwarder) portForwardResources(ctx context.Context, resources []*latest.PortForwardResource) {
	var wg sync.WaitGroup

View on GitHub (pinned to a1189de023)

Solutions

1. Fix the template syntax in the portForward namespace field (balanced {{ }} and valid field names)
2. Define the referenced environment variable in the shell/CI before running skaffold
3. Use a literal namespace string instead of a template if templating is unnecessary
4. Validate the config with skaffold config or skaffold dev --dry-run style checks before deploy

Example fix

# before (skaffold.yaml)
portForward:
  - resourceType: pod
    resourceName: web
    namespace: {{.MISSING_NS}}
# after
export NAMESPACE=my-ns  # or fix the template
portForward:
  - resourceType: pod
    resourceName: web
    namespace: {{.NAMESPACE}}

func validNamespaceTemplate(ns string) error {
    if ns == "" {
        return nil
    }
    if strings.Count(ns, "{{") != strings.Count(ns, "}}") {
        return fmt.Errorf("unbalanced template braces in namespace %q", ns)
    }
    return nil
}

if err := applyWithTemplate(res); err != nil {
    if strings.Contains(err.Error(), "namespace template") {
        return fmt.Errorf("fix portForward.namespace in skaffold.yaml: %v", err)
    }
    return err
}

When it happens

Trigger: PortForwardResource.Namespace is non-empty and util.ExpandEnvTemplateOrFail(resource.Namespace, nil) errors during Start's resource preparation — caused by malformed Go template syntax or an undefined environment variable in skaffold.yaml's portForward.namespace.

Common situations: skaffold.yaml has portForward namespace like {{.MISSING_VAR}} or {{NAMESPACE} (unbalanced brace); CI environment lacks a variable set locally; copy-pasted template using wrong delimiters.

Related errors

• cannot parse the name template on user defined port forwarde
• cannot parse the release namespace template: %w
• bucket name is empty
• INSPECT_PROFILE_NOT_FOUND_ERR
• cannot resolve active Kubernetes context - multiple contexts

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/00a7ee459c29e89d. Report an issue: GitHub.