kubernetes/kops · error

unable to render template: %s, error: %s

Error message

unable to render template: %s, error: %s

What it means

Returned by RunToolBoxTemplate when templater.Render fails to render a template's content with the given context values and snippets. The templater performs Go text/template-like substitution; errors arise from template syntax problems or, when --fail-on-missing is set, from context keys referenced in the template that are absent from the values file. The template path and renderer error are wrapped in the message.

Source

Thrown at cmd/kops/toolbox_template.go:184

	}

	channel, err := kopsapi.LoadChannel(f.VFSContext(), options.channel)
	if err != nil {
		return fmt.Errorf("error loading channel %q: %v", options.channel, err)
	}

	// @step: render each of the templates, splitting on the documents
	r := templater.NewTemplater(channel)
	var documents []string
	for _, x := range templates {
		content, err := os.ReadFile(x)
		if err != nil {
			return fmt.Errorf("unable to read template: %s, error: %s", x, err)
		}

		rendered, err := r.Render(string(content), context, snippets, options.failOnMissing)
		if err != nil {
			return fmt.Errorf("unable to render template: %s, error: %s", x, err)
		}
		// @check if the content is zero ignore it
		if len(rendered) <= 0 {
			continue
		}

		if !options.formatYAML {
			documents = append(documents, strings.Split(rendered, "---\n")...)
			continue
		}

		for _, x := range strings.Split(rendered, "---\n") {
			var data map[string]interface{}
			if err := yaml.Unmarshal([]byte(x), &data); err != nil {
				return fmt.Errorf("unable to unmarshall content from template: %s, error: %s", x, err)
			}
			if len(data) <= 0 {
				continue

View on GitHub (pinned to 4c8573c808)

Solutions

1. Inspect the wrapped error for the exact template construct that failed; fix the syntax at the reported location
2. If it's a missing key: add the key to your --values file, or remove --fail-on-missing if a default/empty render is acceptable
3. Verify template delimiters/functions are correct: match them against a known-good template in the kOps repo examples
4. Re-render with a minimal values file to isolate which variable breaks the render
5. Check snippets included into the template for stray {{ }} markup

Example fix

// before (template)
clusterName: {{ .clusterNam }}

// after
clusterName: {{ .clusterName }}

for key := range extractTemplateKeys(templateText) {
    if _, ok := context[key]; !ok && failOnMissing {
        return fmt.Errorf("context key %q missing but required by template", key)
    }
}

rendered, err := r.Render(content, context, snippets, failOnMissing)
if err != nil {
    if failOnMissing && strings.Contains(err.Error(), "missing") {
        return fmt.Errorf("add missing keys to --values or drop --fail-on-missing: %w", err)
    }
    return fmt.Errorf("fix template syntax: %w", err)
}

When it happens

Trigger: Rendering a template containing invalid template syntax (unclosed {{ }}, bad functions/pipelines) or — with failOnMissing enabled — referencing {{ .someKey }} where "someKey" is not defined in the --values/context map.

Common situations: Missing key in the --values YAML that the template expects (with strict mode on); typos in template variables; pasting snippets with stray {{ }} sequences; incompatible template syntax after upgrading kOps or hand-editing templates; multiline expressions the parser rejects.

Related errors

• invalid InstanceGroup name: %v
• spec.PublicKey is required
• adding keypair to %q is not supported
• unable to parse YAML %v: %v
• error adding SSH public key: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/101e934e2fb9c3bc. Report an issue: GitHub.